// Copyright (c) 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "gpu/command_buffer/service/gles2_cmd_decoder_passthrough.h"

#include <string>
#include <utility>

#include "base/callback.h"
#include "base/strings/string_split.h"
#include "gpu/command_buffer/service/command_buffer_service.h"
#include "gpu/command_buffer/service/decoder_client.h"
#include "gpu/command_buffer/service/feature_info.h"
#include "gpu/command_buffer/service/gl_utils.h"
#include "gpu/command_buffer/service/gpu_fence_manager.h"
#include "gpu/command_buffer/service/gpu_tracer.h"
#include "gpu/command_buffer/service/passthrough_discardable_manager.h"
#include "gpu/command_buffer/service/program_cache.h"
#include "gpu/command_buffer/service/shared_image_representation.h"
#include "ui/gl/gl_version_info.h"

namespace gpu {
namespace gles2 {

namespace {
template <typename ClientType, typename ServiceType, typename DeleteFunction>
void DeleteServiceObjects(ClientServiceMap<ClientType, ServiceType>* id_map,
                          bool have_context,
                          DeleteFunction delete_function) {
  if (have_context) {
    id_map->ForEach(delete_function);
  }

  id_map->Clear();
}

template <typename ClientType, typename ServiceType, typename ResultType>
bool GetClientID(const ClientServiceMap<ClientType, ServiceType>* map,
                 ResultType service_id,
                 ResultType* result) {
  ClientType client_id = 0;
  if (!map->GetClientID(static_cast<ServiceType>(service_id), &client_id)) {
    return false;
  }
  *result = static_cast<ResultType>(client_id);
  return true;
}

void ResizeRenderbuffer(gl::GLApi* api,
                        GLuint renderbuffer,
                        const gfx::Size& size,
                        GLsizei samples,
                        GLenum internal_format,
                        const FeatureInfo* feature_info) {
  ScopedRenderbufferBindingReset scoped_renderbuffer_reset(api);

  api->glBindRenderbufferEXTFn(GL_RENDERBUFFER, renderbuffer);
  if (samples > 0) {
    DCHECK(feature_info->feature_flags().chromium_framebuffer_multisample);
    api->glRenderbufferStorageMultisampleFn(
        GL_RENDERBUFFER, samples, internal_format, size.width(), size.height());
  } else {
    api->glRenderbufferStorageEXTFn(GL_RENDERBUFFER, internal_format,
                                    size.width(), size.height());
  }
}

void RequestExtensions(gl::GLApi* api,
                       const gfx::ExtensionSet& requestable_extensions,
                       const char* const* extensions_to_request,
                       size_t count) {
  for (size_t i = 0; i < count; i++) {
    if (gfx::HasExtension(requestable_extensions, extensions_to_request[i])) {
      // Request the intersection of the two sets
      api->glRequestExtensionANGLEFn(extensions_to_request[i]);
    }
  }
}

void APIENTRY PassthroughGLDebugMessageCallback(GLenum source,
                                                GLenum type,
                                                GLuint id,
                                                GLenum severity,
                                                GLsizei length,
                                                const GLchar* message,
                                                const GLvoid* user_param) {
  DCHECK(user_param != nullptr);
  GLES2DecoderPassthroughImpl* command_decoder =
      static_cast<GLES2DecoderPassthroughImpl*>(const_cast<void*>(user_param));
  command_decoder->OnDebugMessage(source, type, id, severity, length, message);
  LogGLDebugMessage(source, type, id, severity, length, message,
                    command_decoder->GetLogger());
}

void RunCallbacks(std::vector<base::OnceClosure> callbacks) {
  for (base::OnceClosure& callback : callbacks) {
    std::move(callback).Run();
  }
}

// Converts texture targets to texture binding types.  Does not validate the
// input.
GLenum TextureTargetToTextureType(GLenum texture_target) {
  switch (texture_target) {
    case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
    case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
    case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
    case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
    case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
    case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
      return GL_TEXTURE_CUBE_MAP;

    default:
      return texture_target;
  }
}

void UpdateBoundTexturePassthroughSize(gl::GLApi* api,
                                       TexturePassthrough* texture) {
  GLint texture_memory_size = 0;
  api->glGetTexParameterivFn(texture->target(), GL_MEMORY_SIZE_ANGLE,
                             &texture_memory_size);

  texture->SetEstimatedSize(texture_memory_size);
}

}  // anonymous namespace

GLES2DecoderPassthroughImpl::TexturePendingBinding::TexturePendingBinding(
    GLenum target,
    GLuint unit,
    base::WeakPtr<TexturePassthrough> texture)
    : target(target), unit(unit), texture(std::move(texture)) {}

GLES2DecoderPassthroughImpl::TexturePendingBinding::TexturePendingBinding(
    const TexturePendingBinding& other) = default;

GLES2DecoderPassthroughImpl::TexturePendingBinding::TexturePendingBinding(
    TexturePendingBinding&& other) = default;

GLES2DecoderPassthroughImpl::TexturePendingBinding::~TexturePendingBinding() =
    default;

GLES2DecoderPassthroughImpl::TexturePendingBinding&
GLES2DecoderPassthroughImpl::TexturePendingBinding::operator=(
    const TexturePendingBinding& other) = default;

GLES2DecoderPassthroughImpl::TexturePendingBinding&
GLES2DecoderPassthroughImpl::TexturePendingBinding::operator=(
    TexturePendingBinding&& other) = default;

PassthroughResources::PassthroughResources() : texture_object_map(nullptr) {}
PassthroughResources::~PassthroughResources() = default;

void PassthroughResources::DestroyPendingTextures(bool has_context) {
  if (!has_context) {
    for (scoped_refptr<TexturePassthrough> iter :
         textures_pending_destruction) {
      iter->MarkContextLost();
    }
  }
  textures_pending_destruction.clear();
}

bool PassthroughResources::HasTexturesPendingDestruction() const {
  return !textures_pending_destruction.empty();
}

void PassthroughResources::Destroy(gl::GLApi* api) {
  bool have_context = !!api;
  // Only delete textures that are not referenced by a TexturePassthrough
  // object, they handle their own deletion once all references are lost
  DeleteServiceObjects(&texture_id_map, have_context,
                       [this, api](GLuint client_id, GLuint texture) {
                         if (!texture_object_map.HasClientID(client_id)) {
                           api->glDeleteTexturesFn(1, &texture);
                         }
                       });
  DeleteServiceObjects(&buffer_id_map, have_context,
                       [api](GLuint client_id, GLuint buffer) {
                         api->glDeleteBuffersARBFn(1, &buffer);
                       });
  DeleteServiceObjects(&renderbuffer_id_map, have_context,
                       [api](GLuint client_id, GLuint renderbuffer) {
                         api->glDeleteRenderbuffersEXTFn(1, &renderbuffer);
                       });
  DeleteServiceObjects(&sampler_id_map, have_context,
                       [api](GLuint client_id, GLuint sampler) {
                         api->glDeleteSamplersFn(1, &sampler);
                       });
  DeleteServiceObjects(&program_id_map, have_context,
                       [api](GLuint client_id, GLuint program) {
                         api->glDeleteProgramFn(program);
                       });
  DeleteServiceObjects(&shader_id_map, have_context,
                       [api](GLuint client_id, GLuint shader) {
                         api->glDeleteShaderFn(shader);
                       });
  DeleteServiceObjects(&sync_id_map, have_context,
                       [api](GLuint client_id, uintptr_t sync) {
                         api->glDeleteSyncFn(reinterpret_cast<GLsync>(sync));
                       });

  if (!have_context) {
    texture_object_map.ForEach(
        [](GLuint client_id, scoped_refptr<TexturePassthrough> texture) {
          texture->MarkContextLost();
        });
    for (const auto& pair : texture_shared_image_map) {
      pair.second->OnContextLost();
    }
  }
  texture_object_map.Clear();
  texture_shared_image_map.clear();
  DestroyPendingTextures(have_context);
}

ScopedFramebufferBindingReset::ScopedFramebufferBindingReset(gl::GLApi* api)
    : api_(api), draw_framebuffer_(0), read_framebuffer_(0) {
  api_->glGetIntegervFn(GL_DRAW_FRAMEBUFFER_BINDING, &draw_framebuffer_);
  api_->glGetIntegervFn(GL_READ_FRAMEBUFFER_BINDING, &read_framebuffer_);
}

ScopedFramebufferBindingReset::~ScopedFramebufferBindingReset() {
  api_->glBindFramebufferEXTFn(GL_DRAW_FRAMEBUFFER, draw_framebuffer_);
  api_->glBindFramebufferEXTFn(GL_READ_FRAMEBUFFER, read_framebuffer_);
}

ScopedRenderbufferBindingReset::ScopedRenderbufferBindingReset(gl::GLApi* api)
    : api_(api), renderbuffer_(0) {
  api_->glGetIntegervFn(GL_RENDERBUFFER_BINDING, &renderbuffer_);
}

ScopedRenderbufferBindingReset::~ScopedRenderbufferBindingReset() {
  api_->glBindRenderbufferEXTFn(GL_RENDERBUFFER, renderbuffer_);
}

ScopedTexture2DBindingReset::ScopedTexture2DBindingReset(gl::GLApi* api)
    : api_(api), texture_(0) {
  api_->glGetIntegervFn(GL_TEXTURE_2D_BINDING_EXT, &texture_);
}

ScopedTexture2DBindingReset::~ScopedTexture2DBindingReset() {
  api_->glBindTextureFn(GL_TEXTURE_2D, texture_);
}

GLES2DecoderPassthroughImpl::PendingQuery::PendingQuery() = default;
GLES2DecoderPassthroughImpl::PendingQuery::~PendingQuery() {
  // Run all callbacks when a query is destroyed even if it did not complete.
  // This avoids leaks due to outstandsing callbacks.
  RunCallbacks(std::move(callbacks));
}

GLES2DecoderPassthroughImpl::PendingQuery::PendingQuery(PendingQuery&&) =
    default;
GLES2DecoderPassthroughImpl::PendingQuery&
GLES2DecoderPassthroughImpl::PendingQuery::operator=(PendingQuery&&) = default;

GLES2DecoderPassthroughImpl::ActiveQuery::ActiveQuery() = default;
GLES2DecoderPassthroughImpl::ActiveQuery::~ActiveQuery() = default;
GLES2DecoderPassthroughImpl::ActiveQuery::ActiveQuery(ActiveQuery&&) = default;
GLES2DecoderPassthroughImpl::ActiveQuery&
GLES2DecoderPassthroughImpl::ActiveQuery::operator=(ActiveQuery&&) = default;

GLES2DecoderPassthroughImpl::BoundTexture::BoundTexture() = default;
GLES2DecoderPassthroughImpl::BoundTexture::~BoundTexture() = default;
GLES2DecoderPassthroughImpl::BoundTexture::BoundTexture(const BoundTexture&) =
    default;
GLES2DecoderPassthroughImpl::BoundTexture::BoundTexture(BoundTexture&&) =
    default;
GLES2DecoderPassthroughImpl::BoundTexture&
GLES2DecoderPassthroughImpl::BoundTexture::operator=(const BoundTexture&) =
    default;
GLES2DecoderPassthroughImpl::BoundTexture&
GLES2DecoderPassthroughImpl::BoundTexture::operator=(BoundTexture&&) = default;

GLES2DecoderPassthroughImpl::PendingReadPixels::PendingReadPixels() = default;
GLES2DecoderPassthroughImpl::PendingReadPixels::~PendingReadPixels() = default;
GLES2DecoderPassthroughImpl::PendingReadPixels::PendingReadPixels(
    PendingReadPixels&&) = default;
GLES2DecoderPassthroughImpl::PendingReadPixels&
GLES2DecoderPassthroughImpl::PendingReadPixels::operator=(PendingReadPixels&&) =
    default;

GLES2DecoderPassthroughImpl::BufferShadowUpdate::BufferShadowUpdate() = default;
GLES2DecoderPassthroughImpl::BufferShadowUpdate::~BufferShadowUpdate() =
    default;
GLES2DecoderPassthroughImpl::BufferShadowUpdate::BufferShadowUpdate(
    BufferShadowUpdate&&) = default;
GLES2DecoderPassthroughImpl::BufferShadowUpdate&
GLES2DecoderPassthroughImpl::BufferShadowUpdate::operator=(
    BufferShadowUpdate&&) = default;

GLES2DecoderPassthroughImpl::EmulatedColorBuffer::EmulatedColorBuffer(
    gl::GLApi* api,
    const EmulatedDefaultFramebufferFormat& format_in)
    : api(api), format(format_in) {
  ScopedTexture2DBindingReset scoped_texture_reset(api);

  GLuint color_buffer_texture = 0;
  api->glGenTexturesFn(1, &color_buffer_texture);
  api->glBindTextureFn(GL_TEXTURE_2D, color_buffer_texture);
  api->glTexParameteriFn(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  api->glTexParameteriFn(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  api->glTexParameteriFn(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  api->glTexParameteriFn(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  texture = new TexturePassthrough(color_buffer_texture, GL_TEXTURE_2D);
}

GLES2DecoderPassthroughImpl::EmulatedColorBuffer::~EmulatedColorBuffer() =
    default;

void GLES2DecoderPassthroughImpl::EmulatedColorBuffer::Resize(
    const gfx::Size& new_size) {
  if (size == new_size)
    return;
  size = new_size;

  ScopedTexture2DBindingReset scoped_texture_reset(api);

  DCHECK(texture);
  DCHECK(texture->target() == GL_TEXTURE_2D);

  api->glBindTextureFn(texture->target(), texture->service_id());
  api->glTexImage2DFn(texture->target(), 0,
                      format.color_texture_internal_format, size.width(),
                      size.height(), 0, format.color_texture_format,
                      format.color_texture_type, nullptr);
  UpdateBoundTexturePassthroughSize(api, texture.get());
}

void GLES2DecoderPassthroughImpl::EmulatedColorBuffer::Destroy(
    bool have_context) {
  if (!have_context) {
    texture->MarkContextLost();
  }
  texture = nullptr;
}

GLES2DecoderPassthroughImpl::EmulatedDefaultFramebuffer::
    EmulatedDefaultFramebuffer(
        gl::GLApi* api,
        const EmulatedDefaultFramebufferFormat& format_in,
        const FeatureInfo* feature_info)
    : api(api), format(format_in) {
  ScopedFramebufferBindingReset scoped_fbo_reset(api);
  ScopedRenderbufferBindingReset scoped_renderbuffer_reset(api);

  api->glGenFramebuffersEXTFn(1, &framebuffer_service_id);
  api->glBindFramebufferEXTFn(GL_FRAMEBUFFER, framebuffer_service_id);

  if (format.samples > 0) {
    api->glGenRenderbuffersEXTFn(1, &color_buffer_service_id);
    api->glBindRenderbufferEXTFn(GL_RENDERBUFFER, color_buffer_service_id);
    api->glFramebufferRenderbufferEXTFn(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                        GL_RENDERBUFFER,
                                        color_buffer_service_id);
  } else {
    color_texture.reset(new EmulatedColorBuffer(api, format));
    api->glFramebufferTexture2DEXTFn(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                     GL_TEXTURE_2D,
                                     color_texture->texture->service_id(), 0);
  }

  if (format.depth_stencil_internal_format != GL_NONE) {
    DCHECK(format.depth_internal_format == GL_NONE &&
           format.stencil_internal_format == GL_NONE);
    api->glGenRenderbuffersEXTFn(1, &depth_stencil_buffer_service_id);
    api->glBindRenderbufferEXTFn(GL_RENDERBUFFER,
                                 depth_stencil_buffer_service_id);
    if (feature_info->gl_version_info().IsAtLeastGLES(3, 0) ||
        feature_info->feature_flags().angle_webgl_compatibility) {
      api->glFramebufferRenderbufferEXTFn(
          GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER,
          depth_stencil_buffer_service_id);
    } else {
      api->glFramebufferRenderbufferEXTFn(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
                                          GL_RENDERBUFFER,
                                          depth_stencil_buffer_service_id);
      api->glFramebufferRenderbufferEXTFn(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT,
                                          GL_RENDERBUFFER,
                                          depth_stencil_buffer_service_id);
    }
  } else {
    if (format.depth_internal_format != GL_NONE) {
      api->glGenRenderbuffersEXTFn(1, &depth_buffer_service_id);
      api->glBindRenderbufferEXTFn(GL_RENDERBUFFER, depth_buffer_service_id);
      api->glFramebufferRenderbufferEXTFn(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
                                          GL_RENDERBUFFER,
                                          depth_buffer_service_id);
    }

    if (format.stencil_internal_format != GL_NONE) {
      api->glGenRenderbuffersEXTFn(1, &stencil_buffer_service_id);
      api->glBindRenderbufferEXTFn(GL_RENDERBUFFER, stencil_buffer_service_id);
      api->glFramebufferRenderbufferEXTFn(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT,
                                          GL_RENDERBUFFER,
                                          stencil_buffer_service_id);
    }
  }
}

GLES2DecoderPassthroughImpl::EmulatedDefaultFramebuffer::
    ~EmulatedDefaultFramebuffer() = default;

std::unique_ptr<GLES2DecoderPassthroughImpl::EmulatedColorBuffer>
GLES2DecoderPassthroughImpl::EmulatedDefaultFramebuffer::SetColorBuffer(
    std::unique_ptr<EmulatedColorBuffer> new_color_buffer) {
  DCHECK(color_texture != nullptr && new_color_buffer != nullptr);
  DCHECK(color_texture->size == new_color_buffer->size);
  std::unique_ptr<EmulatedColorBuffer> old_buffer(std::move(color_texture));
  color_texture = std::move(new_color_buffer);

  // Bind the new texture to this FBO
  ScopedFramebufferBindingReset scoped_fbo_reset(api);
  api->glBindFramebufferEXTFn(GL_FRAMEBUFFER, framebuffer_service_id);
  api->glFramebufferTexture2DEXTFn(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                   GL_TEXTURE_2D,
                                   color_texture->texture->service_id(), 0);

  return old_buffer;
}

void GLES2DecoderPassthroughImpl::EmulatedDefaultFramebuffer::Blit(
    EmulatedColorBuffer* target) {
  DCHECK(target != nullptr);
  DCHECK(target->size == size);

  ScopedFramebufferBindingReset scoped_fbo_reset(api);

  api->glBindFramebufferEXTFn(GL_READ_FRAMEBUFFER, framebuffer_service_id);

  GLuint temp_fbo;
  api->glGenFramebuffersEXTFn(1, &temp_fbo);
  api->glBindFramebufferEXTFn(GL_DRAW_FRAMEBUFFER, temp_fbo);
  api->glFramebufferTexture2DEXTFn(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                   GL_TEXTURE_2D, target->texture->service_id(),
                                   0);

  api->glBlitFramebufferFn(0, 0, size.width(), size.height(), 0, 0,
                           target->size.width(), target->size.height(),
                           GL_COLOR_BUFFER_BIT, GL_NEAREST);

  api->glDeleteFramebuffersEXTFn(1, &temp_fbo);
}

bool GLES2DecoderPassthroughImpl::EmulatedDefaultFramebuffer::Resize(
    const gfx::Size& new_size,
    const FeatureInfo* feature_info) {
  DCHECK(!new_size.IsEmpty());
  if (size == new_size) {
    return true;
  }
  size = new_size;

  if (color_buffer_service_id != 0) {
    ResizeRenderbuffer(api, color_buffer_service_id, size, format.samples,
                       format.color_renderbuffer_internal_format, feature_info);
  }
  if (color_texture)
    color_texture->Resize(size);
  if (depth_stencil_buffer_service_id != 0) {
    ResizeRenderbuffer(api, depth_stencil_buffer_service_id, size,
                       format.samples, format.depth_stencil_internal_format,
                       feature_info);
  }
  if (depth_buffer_service_id != 0) {
    ResizeRenderbuffer(api, depth_buffer_service_id, size, format.samples,
                       format.depth_internal_format, feature_info);
  }
  if (stencil_buffer_service_id != 0) {
    ResizeRenderbuffer(api, stencil_buffer_service_id, size, format.samples,
                       format.stencil_internal_format, feature_info);
  }

  // Check that the framebuffer is complete
  {
    ScopedFramebufferBindingReset scoped_fbo_reset(api);
    api->glBindFramebufferEXTFn(GL_FRAMEBUFFER, framebuffer_service_id);
    if (api->glCheckFramebufferStatusEXTFn(GL_FRAMEBUFFER) !=
        GL_FRAMEBUFFER_COMPLETE) {
      LOG(ERROR)
          << "GLES2DecoderPassthroughImpl::ResizeOffscreenFramebuffer failed "
          << "because the resulting framebuffer was not complete.";
      return false;
    }
  }

  DCHECK(color_texture == nullptr || color_texture->size == size);

  return true;
}

void GLES2DecoderPassthroughImpl::EmulatedDefaultFramebuffer::Destroy(
    bool have_context) {
  if (have_context) {
    api->glDeleteFramebuffersEXTFn(1, &framebuffer_service_id);
    framebuffer_service_id = 0;

    api->glDeleteRenderbuffersEXTFn(1, &color_buffer_service_id);
    color_buffer_service_id = 0;

    api->glDeleteRenderbuffersEXTFn(1, &depth_stencil_buffer_service_id);
    color_buffer_service_id = 0;

    api->glDeleteRenderbuffersEXTFn(1, &depth_buffer_service_id);
    depth_buffer_service_id = 0;

    api->glDeleteRenderbuffersEXTFn(1, &stencil_buffer_service_id);
    stencil_buffer_service_id = 0;
  }
  if (color_texture) {
    color_texture->Destroy(have_context);
  }
}

GLES2DecoderPassthroughImpl::GLES2DecoderPassthroughImpl(
    DecoderClient* client,
    CommandBufferServiceBase* command_buffer_service,
    Outputter* outputter,
    ContextGroup* group)
    : GLES2Decoder(command_buffer_service, outputter),
      client_(client),
      commands_to_process_(0),
      debug_marker_manager_(),
      logger_(&debug_marker_manager_,
              base::BindRepeating(&DecoderClient::OnConsoleMessage,
                                  base::Unretained(client_),
                                  0)),
      surface_(),
      context_(),
      offscreen_(false),
      group_(group),
      feature_info_(new FeatureInfo(group->feature_info()->workarounds(),
                                    group->gpu_feature_info())),
      emulated_back_buffer_(nullptr),
      offscreen_single_buffer_(false),
      offscreen_target_buffer_preserved_(false),
      create_color_buffer_count_for_test_(0),
      max_2d_texture_size_(0),
      bound_draw_framebuffer_(0),
      bound_read_framebuffer_(0),
      gpu_decoder_category_(TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(
          TRACE_DISABLED_BY_DEFAULT("gpu.decoder"))),
      gpu_trace_level_(2),
      gpu_trace_commands_(false),
      gpu_debug_commands_(false),
      has_robustness_extension_(false),
      context_lost_(false),
      reset_by_robustness_extension_(false),
      lose_context_when_out_of_memory_(false),
      weak_ptr_factory_(this) {
  DCHECK(client);
  DCHECK(group);
}

GLES2DecoderPassthroughImpl::~GLES2DecoderPassthroughImpl() = default;

GLES2Decoder::Error GLES2DecoderPassthroughImpl::DoCommands(
    unsigned int num_commands,
    const volatile void* buffer,
    int num_entries,
    int* entries_processed) {
  if (gpu_debug_commands_) {
    return DoCommandsImpl<true>(num_commands, buffer, num_entries,
                                entries_processed);
  } else {
    return DoCommandsImpl<false>(num_commands, buffer, num_entries,
                                 entries_processed);
  }
}

template <bool DebugImpl>
GLES2Decoder::Error GLES2DecoderPassthroughImpl::DoCommandsImpl(
    unsigned int num_commands,
    const volatile void* buffer,
    int num_entries,
    int* entries_processed) {
  commands_to_process_ = num_commands;
  error::Error result = error::kNoError;
  const volatile CommandBufferEntry* cmd_data =
      static_cast<const volatile CommandBufferEntry*>(buffer);
  int process_pos = 0;
  unsigned int command = 0;

  while (process_pos < num_entries && result == error::kNoError &&
         commands_to_process_--) {
    const unsigned int size = cmd_data->value_header.size;
    command = cmd_data->value_header.command;

    if (size == 0) {
      result = error::kInvalidSize;
      break;
    }

    // size can't overflow because it is 21 bits.
    if (static_cast<int>(size) + process_pos > num_entries) {
      result = error::kOutOfBounds;
      break;
    }

    if (DebugImpl && log_commands()) {
      LOG(ERROR) << "[" << logger_.GetLogPrefix() << "]"
                 << "cmd: " << GetCommandName(command);
    }

    const unsigned int arg_count = size - 1;
    unsigned int command_index = command - kFirstGLES2Command;
    if (command_index < arraysize(command_info)) {
      const CommandInfo& info = command_info[command_index];
      unsigned int info_arg_count = static_cast<unsigned int>(info.arg_count);
      if ((info.arg_flags == cmd::kFixed && arg_count == info_arg_count) ||
          (info.arg_flags == cmd::kAtLeastN && arg_count >= info_arg_count)) {
        bool doing_gpu_trace = false;
        if (DebugImpl && gpu_trace_commands_) {
          if (CMD_FLAG_GET_TRACE_LEVEL(info.cmd_flags) <= gpu_trace_level_) {
            doing_gpu_trace = true;
            gpu_tracer_->Begin(TRACE_DISABLED_BY_DEFAULT("gpu.decoder"),
                               GetCommandName(command), kTraceDecoder);
          }
        }

        if (DebugImpl) {
          VerifyServiceTextureObjectsExist();
        }

        uint32_t immediate_data_size = (arg_count - info_arg_count) *
                                       sizeof(CommandBufferEntry);  // NOLINT
        if (info.cmd_handler) {
          result = (this->*info.cmd_handler)(immediate_data_size, cmd_data);
        } else {
          result = error::kUnknownCommand;
        }

        if (DebugImpl && doing_gpu_trace) {
          gpu_tracer_->End(kTraceDecoder);
        }
      } else {
        result = error::kInvalidArguments;
      }
    } else {
      result = DoCommonCommand(command, arg_count, cmd_data);
    }

    if (result == error::kNoError && context_lost_) {
      result = error::kLostContext;
    }

    if (result != error::kDeferCommandUntilLater) {
      process_pos += size;
      cmd_data += size;
    }
  }

  if (entries_processed)
    *entries_processed = process_pos;

  return result;
}

base::WeakPtr<DecoderContext> GLES2DecoderPassthroughImpl::AsWeakPtr() {
  return weak_ptr_factory_.GetWeakPtr();
}

gpu::ContextResult GLES2DecoderPassthroughImpl::Initialize(
    const scoped_refptr<gl::GLSurface>& surface,
    const scoped_refptr<gl::GLContext>& context,
    bool offscreen,
    const DisallowedFeatures& disallowed_features,
    const ContextCreationAttribs& attrib_helper) {
  TRACE_EVENT0("gpu", "GLES2DecoderPassthroughImpl::Initialize");
  DCHECK(context->IsCurrent(surface.get()));
  api_ = gl::g_current_gl_context;
  // Take ownership of the context and surface. The surface can be replaced
  // with SetSurface.
  context_ = context;
  surface_ = surface;
  offscreen_ = offscreen;

  // Create GPU Tracer for timing values.
  gpu_tracer_.reset(new GPUTracer(this));

  gpu_fence_manager_.reset(new GpuFenceManager());

  auto result =
      group_->Initialize(this, attrib_helper.context_type, disallowed_features);
  if (result != gpu::ContextResult::kSuccess) {
    // Must not destroy ContextGroup if it is not initialized.
    group_ = nullptr;
    Destroy(true);
    return result;
  }

  // Extensions that are enabled via emulation on the client side or needed for
  // basic command buffer functionality.  Make sure they are always enabled.
  if (IsWebGLContextType(attrib_helper.context_type)) {
    // Grab the extensions that are requestable
    gfx::ExtensionSet requestable_extensions(
        gl::GetRequestableGLExtensionsFromCurrentContext());

    static constexpr const char* kRequiredFunctionalityExtensions[] = {
        "GL_ANGLE_memory_size",   "GL_CHROMIUM_bind_uniform_location",
        "GL_CHROMIUM_sync_query", "GL_EXT_debug_marker",
        "GL_KHR_debug",           "GL_NV_fence",
    };
    RequestExtensions(api(), requestable_extensions,
                      kRequiredFunctionalityExtensions,
                      arraysize(kRequiredFunctionalityExtensions));

    if (request_optional_extensions_) {
      static constexpr const char* kOptionalFunctionalityExtensions[] = {
          "GL_ANGLE_depth_texture",
          "GL_ANGLE_framebuffer_blit",
          "GL_ANGLE_framebuffer_multisample",
          "GL_ANGLE_instanced_arrays",
          "GL_ANGLE_pack_reverse_row_order",
          "GL_ANGLE_texture_compression_dxt3",
          "GL_ANGLE_texture_compression_dxt5",
          "GL_ANGLE_texture_usage",
          "GL_ANGLE_translated_shader_source",
          "GL_CHROMIUM_framebuffer_mixed_samples",
          "GL_CHROMIUM_path_rendering",
          "GL_EXT_blend_minmax",
          "GL_EXT_discard_framebuffer",
          "GL_EXT_disjoint_timer_query",
          "GL_EXT_occlusion_query_boolean",
          "GL_EXT_sRGB",
          "GL_EXT_sRGB_write_control",
          "GL_EXT_texture_compression_dxt1",
          "GL_EXT_texture_compression_s3tc_srgb",
          "GL_EXT_texture_format_BGRA8888",
          "GL_EXT_texture_norm16",
          "GL_EXT_texture_rg",
          "GL_EXT_texture_sRGB_decode",
          "GL_EXT_texture_storage",
          "GL_EXT_unpack_subimage",
          "GL_KHR_parallel_shader_compile",
          "GL_KHR_robust_buffer_access_behavior",
          "GL_KHR_texture_compression_astc_hdr",
          "GL_KHR_texture_compression_astc_ldr",
          "GL_NV_pack_subimage",
          "GL_OES_compressed_ETC1_RGB8_texture",
          "GL_OES_depth32",
          "GL_OES_EGL_image",
          "GL_OES_EGL_image_external",
          "GL_OES_EGL_image_external_essl3",
          "GL_OES_fbo_render_mipmap",
          "GL_OES_packed_depth_stencil",
          "GL_OES_rgb8_rgba8",
          "GL_OES_vertex_array_object",
          "NV_EGL_stream_consumer_external",
      };
      RequestExtensions(api(), requestable_extensions,
                        kOptionalFunctionalityExtensions,
                        arraysize(kOptionalFunctionalityExtensions));
    }

    context->ReinitializeDynamicBindings();
  }

  // Each context initializes its own feature info because some extensions may
  // be enabled dynamically.  Don't disallow any features, leave it up to ANGLE
  // to dynamically enable extensions.
  feature_info_->Initialize(attrib_helper.context_type,
                            true /* is_passthrough_cmd_decoder */,
                            DisallowedFeatures());

  // Check for required extensions
  // TODO(geofflang): verify
  // feature_info_->feature_flags().angle_robust_resource_initialization and
  // api()->glIsEnabledFn(GL_ROBUST_RESOURCE_INITIALIZATION_ANGLE)

#define FAIL_INIT_IF_NOT(feature, message)                       \
  if (!(feature)) {                                              \
    Destroy(true);                                               \
    LOG(ERROR) << "ContextResult::kFatalFailure: " << (message); \
    return gpu::ContextResult::kFatalFailure;                    \
  }

  FAIL_INIT_IF_NOT(feature_info_->feature_flags().angle_robust_client_memory,
                   "missing GL_ANGLE_robust_client_memory");
  FAIL_INIT_IF_NOT(
      feature_info_->feature_flags().chromium_bind_generates_resource,
      "missing GL_CHROMIUM_bind_generates_resource");
  FAIL_INIT_IF_NOT(feature_info_->feature_flags().chromium_copy_texture,
                   "missing GL_CHROMIUM_copy_texture");
  FAIL_INIT_IF_NOT(feature_info_->feature_flags().angle_client_arrays,
                   "missing GL_ANGLE_client_arrays");
  FAIL_INIT_IF_NOT(api()->glIsEnabledFn(GL_CLIENT_ARRAYS_ANGLE) == GL_FALSE,
                   "GL_ANGLE_client_arrays shouldn't be enabled");
  FAIL_INIT_IF_NOT(feature_info_->feature_flags().angle_webgl_compatibility ==
                       IsWebGLContextType(attrib_helper.context_type),
                   "missing GL_ANGLE_webgl_compatibility");
  FAIL_INIT_IF_NOT(feature_info_->feature_flags().angle_request_extension,
                   "missing  GL_ANGLE_request_extension");
  FAIL_INIT_IF_NOT(feature_info_->feature_flags().khr_debug,
                   "missing GL_KHR_debug");
  FAIL_INIT_IF_NOT(
      !IsWebGL2ComputeContextType(attrib_helper.context_type) ||
          feature_info_->feature_flags().khr_robust_buffer_access_behavior,
      "missing GL_KHR_robust_buffer_access_behavior");
  FAIL_INIT_IF_NOT(!attrib_helper.enable_oop_rasterization,
                   "oop rasterization not supported");

#undef FAIL_INIT_IF_NOT

  bind_generates_resource_ = group_->bind_generates_resource();

  resources_ = group_->passthrough_resources();

  mailbox_manager_ = group_->mailbox_manager();

  // Query information about the texture units
  GLint num_texture_units = 0;
  api()->glGetIntegervFn(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS,
                         &num_texture_units);
  if (num_texture_units > static_cast<GLint>(kMaxTextureUnits)) {
    Destroy(true);
    LOG(ERROR) << "kMaxTextureUnits (" << kMaxTextureUnits
               << ") must be at least GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS ("
               << num_texture_units << ").";
    return gpu::ContextResult::kFatalFailure;
  }

  active_texture_unit_ = 0;

  // Initialize the tracked buffer bindings
  bound_buffers_[GL_ARRAY_BUFFER] = 0;
  bound_buffers_[GL_ELEMENT_ARRAY_BUFFER] = 0;
  if (feature_info_->gl_version_info().IsAtLeastGLES(3, 0) ||
      feature_info_->feature_flags().ext_pixel_buffer_object) {
    bound_buffers_[GL_PIXEL_PACK_BUFFER] = 0;
    bound_buffers_[GL_PIXEL_UNPACK_BUFFER] = 0;
  }
  if (feature_info_->gl_version_info().IsAtLeastGLES(3, 0)) {
    bound_buffers_[GL_COPY_READ_BUFFER] = 0;
    bound_buffers_[GL_COPY_WRITE_BUFFER] = 0;
    bound_buffers_[GL_TRANSFORM_FEEDBACK_BUFFER] = 0;
    bound_buffers_[GL_UNIFORM_BUFFER] = 0;
  }
  if (feature_info_->gl_version_info().IsAtLeastGLES(3, 1)) {
    bound_buffers_[GL_ATOMIC_COUNTER_BUFFER] = 0;
    bound_buffers_[GL_SHADER_STORAGE_BUFFER] = 0;
    bound_buffers_[GL_DRAW_INDIRECT_BUFFER] = 0;
    bound_buffers_[GL_DISPATCH_INDIRECT_BUFFER] = 0;
  }

  // For WebGL contexts, log GL errors so they appear in devtools. Otherwise
  // only enable debug logging if requested.
  bool log_non_errors =
      group_->gpu_preferences().enable_gpu_driver_debug_logging;
  InitializeGLDebugLogging(log_non_errors, PassthroughGLDebugMessageCallback,
                           this);

  if (feature_info_->feature_flags().chromium_texture_filtering_hint &&
      feature_info_->feature_flags().is_swiftshader) {
    api()->glHintFn(GL_TEXTURE_FILTERING_HINT_CHROMIUM, GL_NICEST);
  }

  has_robustness_extension_ = feature_info_->feature_flags().khr_robustness ||
                              feature_info_->feature_flags().ext_robustness;
  lose_context_when_out_of_memory_ =
      attrib_helper.lose_context_when_out_of_memory;

  api()->glGetIntegervFn(GL_MAX_TEXTURE_SIZE, &max_2d_texture_size_);
  api()->glGetIntegervFn(GL_MAX_RENDERBUFFER_SIZE, &max_renderbuffer_size_);
  max_offscreen_framebuffer_size_ =
      std::min(max_2d_texture_size_, max_renderbuffer_size_);

  if (offscreen_) {
    offscreen_single_buffer_ = attrib_helper.single_buffer;
    offscreen_target_buffer_preserved_ = attrib_helper.buffer_preserved;
    const bool multisampled_framebuffers_supported =
        feature_info_->feature_flags().chromium_framebuffer_multisample;
    if (attrib_helper.samples > 0 && attrib_helper.sample_buffers > 0 &&
        multisampled_framebuffers_supported && !offscreen_single_buffer_) {
      GLint max_sample_count = 0;
      api()->glGetIntegervFn(GL_MAX_SAMPLES_EXT, &max_sample_count);
      emulated_default_framebuffer_format_.samples =
          std::min(attrib_helper.samples, max_sample_count);
    }

    const bool rgb8_supported = feature_info_->feature_flags().oes_rgb8_rgba8;
    const bool alpha_channel_requested = attrib_helper.alpha_size > 0;
    // The only available default render buffer formats in GLES2 have very
    // little precision.  Don't enable multisampling unless 8-bit render
    // buffer formats are available--instead fall back to 8-bit textures.
    if (rgb8_supported && emulated_default_framebuffer_format_.samples > 0) {
      emulated_default_framebuffer_format_.color_renderbuffer_internal_format =
          alpha_channel_requested ? GL_RGBA8 : GL_RGB8;
    } else {
      emulated_default_framebuffer_format_.samples = 0;
    }

    emulated_default_framebuffer_format_.color_texture_internal_format =
        alpha_channel_requested ? GL_RGBA : GL_RGB;
    emulated_default_framebuffer_format_.color_texture_format =
        emulated_default_framebuffer_format_.color_texture_internal_format;
    emulated_default_framebuffer_format_.color_texture_type = GL_UNSIGNED_BYTE;

    const bool depth24_stencil8_supported =
        feature_info_->feature_flags().packed_depth24_stencil8;
    if ((attrib_helper.depth_size > 0 || attrib_helper.stencil_size > 0) &&
        depth24_stencil8_supported) {
      emulated_default_framebuffer_format_.depth_stencil_internal_format =
          GL_DEPTH24_STENCIL8;
    } else {
      // It may be the case that this depth/stencil combination is not
      // supported, but this will be checked later by CheckFramebufferStatus.
      if (attrib_helper.depth_size > 0) {
        emulated_default_framebuffer_format_.depth_internal_format =
            GL_DEPTH_COMPONENT16;
      }
      if (attrib_helper.stencil_size > 0) {
        emulated_default_framebuffer_format_.stencil_internal_format =
            GL_STENCIL_INDEX8;
      }
    }

    CheckErrorCallbackState();
    emulated_back_buffer_ = std::make_unique<EmulatedDefaultFramebuffer>(
        api(), emulated_default_framebuffer_format_, feature_info_.get());
    // Make sure to use a non-empty offscreen surface so that the framebuffer is
    // complete.
    gfx::Size initial_size(
        std::max(1, attrib_helper.offscreen_framebuffer_size.width()),
        std::max(1, attrib_helper.offscreen_framebuffer_size.height()));
    if (!emulated_back_buffer_->Resize(initial_size, feature_info_.get())) {
      bool was_lost = CheckResetStatus();
      Destroy(true);
      LOG(ERROR) << (was_lost ? "ContextResult::kTransientFailure: "
                              : "ContextResult::kFatalFailure: ")
                 << "Resize of emulated back buffer failed";
      return was_lost ? gpu::ContextResult::kTransientFailure
                      : gpu::ContextResult::kFatalFailure;
    }

    if (CheckErrorCallbackState()) {
      Destroy(true);
      // Errors are considered fatal, including OOM.
      LOG(ERROR)
          << "ContextResult::kFatalFailure: "
             "Creation of the offscreen framebuffer failed because errors were "
             "generated.";
      return gpu::ContextResult::kFatalFailure;
    }

    framebuffer_id_map_.SetIDMapping(
        0, emulated_back_buffer_->framebuffer_service_id);

    // Bind the emulated default framebuffer and initialize the viewport
    api()->glBindFramebufferEXTFn(
        GL_FRAMEBUFFER, emulated_back_buffer_->framebuffer_service_id);
    api()->glViewportFn(0, 0, attrib_helper.offscreen_framebuffer_size.width(),
                        attrib_helper.offscreen_framebuffer_size.height());
  }

  // Initialize the tracked scissor and viewport state and then apply the
  // surface offsets if needed.
  api()->glGetIntegervFn(GL_VIEWPORT, viewport_);
  api()->glGetIntegervFn(GL_SCISSOR_BOX, scissor_);
  ApplySurfaceDrawOffset();

  set_initialized();
  return gpu::ContextResult::kSuccess;
}

void GLES2DecoderPassthroughImpl::Destroy(bool have_context) {
  if (have_context) {
    FlushErrors();
  }

  // Destroy all pending read pixels operations
  for (PendingReadPixels& pending_read_pixels : pending_read_pixels_) {
    if (have_context) {
      api()->glDeleteBuffersARBFn(1, &pending_read_pixels.buffer_service_id);
    } else {
      pending_read_pixels.fence->Invalidate();
    }
  }
  pending_read_pixels_.clear();

  for (auto& bound_texture_type : bound_textures_) {
    for (auto& bound_texture : bound_texture_type) {
      if (!have_context && bound_texture.texture) {
        bound_texture.texture->MarkContextLost();
      }
      bound_texture.texture = nullptr;
    }
  }

  if (resources_) {  // Initialize may not have been called yet.
    for (PassthroughAbstractTextureImpl* iter : abstract_textures_) {
      resources_->textures_pending_destruction.insert(
          iter->OnDecoderWillDestroy());
    }
    abstract_textures_.clear();
    if (have_context) {
      resources_->DestroyPendingTextures(/*has_context=*/true);
    }
  }

  DeleteServiceObjects(&framebuffer_id_map_, have_context,
                       [this](GLuint client_id, GLuint framebuffer) {
                         api()->glDeleteFramebuffersEXTFn(1, &framebuffer);
                       });
  DeleteServiceObjects(&transform_feedback_id_map_, have_context,
                       [this](GLuint client_id, GLuint transform_feedback) {
                         api()->glDeleteTransformFeedbacksFn(
                             1, &transform_feedback);
                       });
  DeleteServiceObjects(&query_id_map_, have_context,
                       [this](GLuint client_id, GLuint query) {
                         api()->glDeleteQueriesFn(1, &query);
                       });
  DeleteServiceObjects(&vertex_array_id_map_, have_context,
                       [this](GLuint client_id, GLuint vertex_array) {
                         api()->glDeleteVertexArraysOESFn(1, &vertex_array);
                       });

  // Destroy the emulated backbuffer
  if (emulated_back_buffer_) {
    emulated_back_buffer_->Destroy(have_context);
    emulated_back_buffer_.reset();
  }

  if (emulated_front_buffer_) {
    emulated_front_buffer_->Destroy(have_context);
    emulated_front_buffer_.reset();
  }

  for (auto& in_use_color_texture : in_use_color_textures_) {
    in_use_color_texture->Destroy(have_context);
  }
  in_use_color_textures_.clear();

  for (auto& available_color_texture : available_color_textures_) {
    available_color_texture->Destroy(have_context);
  }
  available_color_textures_.clear();

  if (gpu_fence_manager_.get()) {
    gpu_fence_manager_->Destroy(have_context);
    gpu_fence_manager_.reset();
  }

  // Destroy the GPU Tracer which may own some in process GPU Timings.
  if (gpu_tracer_) {
    gpu_tracer_->Destroy(have_context);
    gpu_tracer_.reset();
  }

  if (!have_context) {
    for (auto& fence : deschedule_until_finished_fences_) {
      fence->Invalidate();
    }
  }
  deschedule_until_finished_fences_.clear();

  // Destroy the surface before the context, some surface destructors make GL
  // calls.
  surface_ = nullptr;

  if (group_) {
    if (group_->has_program_cache()) {
      group_->get_program_cache()->ResetCacheProgramCallback();
    }

    group_->Destroy(this, have_context);
    group_ = nullptr;
  }

  if (context_.get()) {
    context_->ReleaseCurrent(nullptr);
    context_ = nullptr;
  }
}

void GLES2DecoderPassthroughImpl::SetSurface(
    const scoped_refptr<gl::GLSurface>& surface) {
  DCHECK(context_->IsCurrent(nullptr));
  DCHECK(surface_.get());
  surface_ = surface;
}

void GLES2DecoderPassthroughImpl::ReleaseSurface() {
  if (!context_.get())
    return;
  if (WasContextLost()) {
    DLOG(ERROR) << "  GLES2DecoderImpl: Trying to release lost context.";
    return;
  }
  context_->ReleaseCurrent(surface_.get());
  surface_ = nullptr;
}

void GLES2DecoderPassthroughImpl::TakeFrontBuffer(const Mailbox& mailbox) {
  if (offscreen_single_buffer_) {
    DCHECK(emulated_back_buffer_->color_texture != nullptr);
    mailbox_manager_->ProduceTexture(
        mailbox, emulated_back_buffer_->color_texture->texture.get());
    return;
  }

  if (!emulated_front_buffer_) {
    DLOG(ERROR) << "Called TakeFrontBuffer on a non-offscreen context";
    return;
  }

  mailbox_manager_->ProduceTexture(mailbox,
                                   emulated_front_buffer_->texture.get());
  in_use_color_textures_.push_back(std::move(emulated_front_buffer_));
  emulated_front_buffer_ = nullptr;

  if (available_color_textures_.empty()) {
    // Create a new color texture to use as the front buffer
    emulated_front_buffer_ = std::make_unique<EmulatedColorBuffer>(
        api(), emulated_default_framebuffer_format_);
    emulated_front_buffer_->Resize(emulated_back_buffer_->size);
    create_color_buffer_count_for_test_++;
  } else {
    emulated_front_buffer_ = std::move(available_color_textures_.back());
    available_color_textures_.pop_back();
  }
}

void GLES2DecoderPassthroughImpl::ReturnFrontBuffer(const Mailbox& mailbox,
                                                    bool is_lost) {
  TextureBase* texture = mailbox_manager_->ConsumeTexture(mailbox);
  mailbox_manager_->TextureDeleted(texture);

  if (offscreen_single_buffer_) {
    return;
  }

  auto it = in_use_color_textures_.begin();
  while (it != in_use_color_textures_.end()) {
    if ((*it)->texture == texture) {
      break;
    }
    it++;
  }
  if (it == in_use_color_textures_.end()) {
    DLOG(ERROR) << "Attempting to return a frontbuffer that was not saved.";
    return;
  }

  if (is_lost) {
    (*it)->texture->MarkContextLost();
    (*it)->Destroy(false);
  } else if ((*it)->size != emulated_back_buffer_->size) {
    (*it)->Destroy(true);
  } else {
    available_color_textures_.push_back(std::move(*it));
  }
  in_use_color_textures_.erase(it);
}

bool GLES2DecoderPassthroughImpl::ResizeOffscreenFramebuffer(
    const gfx::Size& size) {
  DCHECK(offscreen_);
  if (!emulated_back_buffer_) {
    LOG(ERROR)
        << "GLES2DecoderPassthroughImpl::ResizeOffscreenFramebuffer called "
        << " with an onscreen framebuffer.";
    return false;
  }

  if (emulated_back_buffer_->size == size) {
    return true;
  }

  if (size.width() < 0 || size.height() < 0 ||
      size.width() > max_offscreen_framebuffer_size_ ||
      size.height() > max_offscreen_framebuffer_size_) {
    LOG(ERROR) << "GLES2DecoderPassthroughImpl::ResizeOffscreenFramebuffer "
                  "failed to allocate storage due to excessive dimensions.";
    return false;
  }

  CheckErrorCallbackState();

  if (!emulated_back_buffer_->Resize(size, feature_info_.get())) {
    LOG(ERROR) << "GLES2DecoderPassthroughImpl::ResizeOffscreenFramebuffer "
                  "failed to resize the emulated framebuffer.";
    return false;
  }

  if (CheckErrorCallbackState()) {
    LOG(ERROR) << "GLES2DecoderPassthroughImpl::ResizeOffscreenFramebuffer "
                  "failed to resize the emulated framebuffer because errors "
                  "were generated.";
    return false;
  }

  // Destroy all the available color textures, they should not be the same size
  // as the back buffer
  for (auto& available_color_texture : available_color_textures_) {
    DCHECK(available_color_texture->size != size);
    available_color_texture->Destroy(true);
  }
  available_color_textures_.clear();

  return true;
}

bool GLES2DecoderPassthroughImpl::MakeCurrent() {
  if (!context_.get())
    return false;

  if (WasContextLost()) {
    LOG(ERROR) << "  GLES2DecoderPassthroughImpl: Trying to make lost context "
                  "current.";
    return false;
  }

  if (!context_->MakeCurrent(surface_.get())) {
    LOG(ERROR)
        << "  GLES2DecoderPassthroughImpl: Context lost during MakeCurrent.";
    MarkContextLost(error::kMakeCurrentFailed);
    group_->LoseContexts(error::kUnknown);
    return false;
  }
  DCHECK_EQ(api(), gl::g_current_gl_context);

  if (CheckResetStatus()) {
    LOG(ERROR) << "  GLES2DecoderPassthroughImpl: Context reset detected after "
                  "MakeCurrent.";
    group_->LoseContexts(error::kUnknown);
    return false;
  }

  // Establish the program binary caching callback.
  if (group_->has_program_cache()) {
    auto program_callback = base::BindRepeating(&DecoderClient::CacheShader,
                                                base::Unretained(client_));
    group_->get_program_cache()->SetCacheProgramCallback(program_callback);
  }

  ProcessReadPixels(false);
  ProcessQueries(false);

  resources_->DestroyPendingTextures(/*has_context=*/true);

  return true;
}

gpu::gles2::GLES2Util* GLES2DecoderPassthroughImpl::GetGLES2Util() {
  return nullptr;
}

gl::GLContext* GLES2DecoderPassthroughImpl::GetGLContext() {
  return context_.get();
}

gl::GLSurface* GLES2DecoderPassthroughImpl::GetGLSurface() {
  return surface_.get();
}

gpu::gles2::ContextGroup* GLES2DecoderPassthroughImpl::GetContextGroup() {
  return group_.get();
}

const FeatureInfo* GLES2DecoderPassthroughImpl::GetFeatureInfo() const {
  return group_->feature_info();
}

gpu::Capabilities GLES2DecoderPassthroughImpl::GetCapabilities() {
  DCHECK(initialized());
  Capabilities caps;

  PopulateNumericCapabilities(&caps, feature_info_.get());

  api()->glGetIntegervFn(GL_BIND_GENERATES_RESOURCE_CHROMIUM,
                         &caps.bind_generates_resource_chromium);
  DCHECK_EQ(caps.bind_generates_resource_chromium != GL_FALSE,
            group_->bind_generates_resource());

  caps.egl_image_external =
      feature_info_->feature_flags().oes_egl_image_external;
  caps.texture_format_astc =
      feature_info_->feature_flags().ext_texture_format_astc;
  caps.texture_format_atc =
      feature_info_->feature_flags().ext_texture_format_atc;
  caps.texture_format_bgra8888 =
      feature_info_->feature_flags().ext_texture_format_bgra8888;
  caps.texture_format_dxt1 =
      feature_info_->feature_flags().ext_texture_format_dxt1;
  caps.texture_format_dxt5 =
      feature_info_->feature_flags().ext_texture_format_dxt5;
  caps.texture_format_etc1 =
      feature_info_->feature_flags().oes_compressed_etc1_rgb8_texture;
  caps.texture_format_etc1_npot = caps.texture_format_etc1;
  caps.texture_rectangle = feature_info_->feature_flags().arb_texture_rectangle;
  caps.texture_usage = feature_info_->feature_flags().angle_texture_usage;
  caps.texture_storage = feature_info_->feature_flags().ext_texture_storage;
  caps.discard_framebuffer =
      feature_info_->feature_flags().ext_discard_framebuffer;
  caps.sync_query = feature_info_->feature_flags().chromium_sync_query;
#if defined(OS_MACOSX)
  // This is unconditionally true on mac, no need to test for it at runtime.
  caps.iosurface = true;
#endif
  caps.blend_equation_advanced =
      feature_info_->feature_flags().blend_equation_advanced;
  caps.blend_equation_advanced_coherent =
      feature_info_->feature_flags().blend_equation_advanced_coherent;
  caps.texture_rg = feature_info_->feature_flags().ext_texture_rg;
  caps.texture_norm16 = feature_info_->feature_flags().ext_texture_norm16;
  caps.texture_half_float_linear =
      feature_info_->feature_flags().enable_texture_half_float_linear;
  caps.color_buffer_half_float_rgba =
      feature_info_->ext_color_buffer_float_available() ||
      feature_info_->ext_color_buffer_half_float_available();
  caps.image_ycbcr_422 =
      feature_info_->feature_flags().chromium_image_ycbcr_422;
  caps.image_ycbcr_420v =
      feature_info_->feature_flags().chromium_image_ycbcr_420v;
  caps.image_ycbcr_420v_disabled_for_video_frames =
      group_->gpu_preferences()
          .disable_biplanar_gpu_memory_buffers_for_video_frames;
  caps.image_xr30 = feature_info_->feature_flags().chromium_image_xr30;
  caps.image_xb30 = feature_info_->feature_flags().chromium_image_xb30;
  caps.max_copy_texture_chromium_size =
      feature_info_->workarounds().max_copy_texture_chromium_size;
  caps.render_buffer_format_bgra8888 =
      feature_info_->feature_flags().ext_render_buffer_format_bgra8888;
  caps.occlusion_query_boolean =
      feature_info_->feature_flags().occlusion_query_boolean;
  caps.timer_queries = feature_info_->feature_flags().ext_disjoint_timer_query;
  caps.gpu_rasterization =
      group_->gpu_feature_info()
          .status_values[GPU_FEATURE_TYPE_GPU_RASTERIZATION] ==
      kGpuFeatureStatusEnabled;
  caps.post_sub_buffer = surface_->SupportsPostSubBuffer();
  caps.surfaceless = !offscreen_ && surface_->IsSurfaceless();
  caps.flips_vertically = !offscreen_ && surface_->FlipsVertically();
  caps.msaa_is_slow = feature_info_->workarounds().msaa_is_slow;
  caps.avoid_stencil_buffers =
      feature_info_->workarounds().avoid_stencil_buffers;
  caps.multisample_compatibility =
      feature_info_->feature_flags().ext_multisample_compatibility;
  caps.dc_layers = !offscreen_ && surface_->SupportsDCLayers();
  caps.commit_overlay_planes = surface_->SupportsCommitOverlayPlanes();
  caps.use_dc_overlays_for_video = surface_->UseOverlaysForVideo();
  caps.protected_video_swap_chain = surface_->SupportsProtectedVideo();
  caps.texture_npot = feature_info_->feature_flags().npot_ok;
  caps.chromium_gpu_fence = feature_info_->feature_flags().chromium_gpu_fence;
  caps.chromium_nonblocking_readback = true;
  caps.num_surface_buffers = surface_->GetBufferCount();
  caps.gpu_memory_buffer_formats =
      feature_info_->feature_flags().gpu_memory_buffer_formats;
  caps.texture_target_exception_list =
      group_->gpu_preferences().texture_target_exception_list;

  return caps;
}

void GLES2DecoderPassthroughImpl::RestoreState(const ContextState* prev_state) {
}

void GLES2DecoderPassthroughImpl::RestoreActiveTexture() const {}

void GLES2DecoderPassthroughImpl::RestoreAllTextureUnitAndSamplerBindings(
    const ContextState* prev_state) const {}

void GLES2DecoderPassthroughImpl::RestoreActiveTextureUnitBinding(
    unsigned int target) const {}

void GLES2DecoderPassthroughImpl::RestoreBufferBinding(unsigned int target) {}

void GLES2DecoderPassthroughImpl::RestoreBufferBindings() const {}

void GLES2DecoderPassthroughImpl::RestoreFramebufferBindings() const {}

void GLES2DecoderPassthroughImpl::RestoreRenderbufferBindings() {}

void GLES2DecoderPassthroughImpl::RestoreGlobalState() const {}

void GLES2DecoderPassthroughImpl::RestoreProgramBindings() const {}

void GLES2DecoderPassthroughImpl::RestoreTextureState(
    unsigned service_id) const {}

void GLES2DecoderPassthroughImpl::RestoreTextureUnitBindings(
    unsigned unit) const {}

void GLES2DecoderPassthroughImpl::RestoreVertexAttribArray(unsigned index) {}

void GLES2DecoderPassthroughImpl::RestoreAllExternalTextureBindingsIfNeeded() {}

void GLES2DecoderPassthroughImpl::RestoreDeviceWindowRectangles() const {}

void GLES2DecoderPassthroughImpl::ClearAllAttributes() const {}

void GLES2DecoderPassthroughImpl::RestoreAllAttributes() const {}

void GLES2DecoderPassthroughImpl::SetIgnoreCachedStateForTest(bool ignore) {}

void GLES2DecoderPassthroughImpl::SetForceShaderNameHashingForTest(bool force) {
}

size_t GLES2DecoderPassthroughImpl::GetSavedBackTextureCountForTest() {
  return in_use_color_textures_.size() + available_color_textures_.size();
}

size_t GLES2DecoderPassthroughImpl::GetCreatedBackTextureCountForTest() {
  return create_color_buffer_count_for_test_;
}

gpu::QueryManager* GLES2DecoderPassthroughImpl::GetQueryManager() {
  return nullptr;
}

void GLES2DecoderPassthroughImpl::SetQueryCallback(unsigned int query_client_id,
                                                   base::OnceClosure callback) {
  GLuint service_id = query_id_map_.GetServiceIDOrInvalid(query_client_id);
  for (auto& pending_query : pending_queries_) {
    if (pending_query.service_id == service_id) {
      pending_query.callbacks.push_back(std::move(callback));
      return;
    }
  }

  VLOG(1) << "GLES2DecoderPassthroughImpl::SetQueryCallback: No pending query "
             "with ID "
          << query_client_id << ". Running the callback immediately.";
  std::move(callback).Run();
}

gpu::gles2::GpuFenceManager* GLES2DecoderPassthroughImpl::GetGpuFenceManager() {
  return gpu_fence_manager_.get();
}

gpu::gles2::FramebufferManager*
GLES2DecoderPassthroughImpl::GetFramebufferManager() {
  return nullptr;
}

gpu::gles2::TransformFeedbackManager*
GLES2DecoderPassthroughImpl::GetTransformFeedbackManager() {
  return nullptr;
}

gpu::gles2::VertexArrayManager*
GLES2DecoderPassthroughImpl::GetVertexArrayManager() {
  return nullptr;
}

gpu::gles2::ImageManager*
GLES2DecoderPassthroughImpl::GetImageManagerForTest() {
  return group_->image_manager();
}

bool GLES2DecoderPassthroughImpl::HasPendingQueries() const {
  return !pending_queries_.empty();
}

void GLES2DecoderPassthroughImpl::ProcessPendingQueries(bool did_finish) {
  // TODO(geofflang): If this returned an error, store it somewhere.
  ProcessQueries(did_finish);
}

bool GLES2DecoderPassthroughImpl::HasMoreIdleWork() const {
  return gpu_tracer_->HasTracesToProcess() || !pending_read_pixels_.empty() ||
         resources_->HasTexturesPendingDestruction();
}

void GLES2DecoderPassthroughImpl::PerformIdleWork() {
  gpu_tracer_->ProcessTraces();
  ProcessReadPixels(false);
}

bool GLES2DecoderPassthroughImpl::HasPollingWork() const {
  return deschedule_until_finished_fences_.size() >= 2;
}

void GLES2DecoderPassthroughImpl::PerformPollingWork() {
  ProcessDescheduleUntilFinished();
}

bool GLES2DecoderPassthroughImpl::GetServiceTextureId(
    uint32_t client_texture_id,
    uint32_t* service_texture_id) {
  return resources_->texture_id_map.GetServiceID(client_texture_id,
                                                 service_texture_id);
}

TextureBase* GLES2DecoderPassthroughImpl::GetTextureBase(uint32_t client_id) {
  scoped_refptr<TexturePassthrough> texture = nullptr;
  if (resources_->texture_object_map.GetServiceID(client_id, &texture)) {
    return texture.get();
  } else {
    return nullptr;
  }
}

bool GLES2DecoderPassthroughImpl::ClearLevel(Texture* texture,
                                             unsigned target,
                                             int level,
                                             unsigned format,
                                             unsigned type,
                                             int xoffset,
                                             int yoffset,
                                             int width,
                                             int height) {
  return true;
}

bool GLES2DecoderPassthroughImpl::ClearCompressedTextureLevel(Texture* texture,
                                                              unsigned target,
                                                              int level,
                                                              unsigned format,
                                                              int width,
                                                              int height) {
  return true;
}

bool GLES2DecoderPassthroughImpl::IsCompressedTextureFormat(unsigned format) {
  return false;
}

bool GLES2DecoderPassthroughImpl::ClearLevel3D(Texture* texture,
                                               unsigned target,
                                               int level,
                                               unsigned format,
                                               unsigned type,
                                               int width,
                                               int height,
                                               int depth) {
  return true;
}

gpu::gles2::ErrorState* GLES2DecoderPassthroughImpl::GetErrorState() {
  return nullptr;
}

void GLES2DecoderPassthroughImpl::WaitForReadPixels(
    base::OnceClosure callback) {}

std::unique_ptr<AbstractTexture>
GLES2DecoderPassthroughImpl::CreateAbstractTexture(GLenum target,
                                                   GLenum internal_format,
                                                   GLsizei width,
                                                   GLsizei height,
                                                   GLsizei depth,
                                                   GLint border,
                                                   GLenum format,
                                                   GLenum type) {
  // We can't support cube maps because the abstract texture does not allow it.
  DCHECK(target != GL_TEXTURE_CUBE_MAP);
  GLuint service_id = 0;
  api()->glGenTexturesFn(1, &service_id);
  scoped_refptr<TexturePassthrough> texture(
      new TexturePassthrough(service_id, target));

  // Unretained is safe, because of the destruction cb.
  std::unique_ptr<PassthroughAbstractTextureImpl> abstract_texture =
      std::make_unique<PassthroughAbstractTextureImpl>(texture, this);

  abstract_textures_.insert(abstract_texture.get());
  return abstract_texture;
}

void GLES2DecoderPassthroughImpl::OnAbstractTextureDestroyed(
    PassthroughAbstractTextureImpl* abstract_texture,
    scoped_refptr<TexturePassthrough> texture) {
  DCHECK(texture);
  abstract_textures_.erase(abstract_texture);
  if (context_->IsCurrent(nullptr)) {
    resources_->DestroyPendingTextures(true);
  } else {
    resources_->textures_pending_destruction.insert(std::move(texture));
  }
}

bool GLES2DecoderPassthroughImpl::WasContextLost() const {
  return context_lost_;
}

bool GLES2DecoderPassthroughImpl::WasContextLostByRobustnessExtension() const {
  return WasContextLost() && reset_by_robustness_extension_;
}

void GLES2DecoderPassthroughImpl::MarkContextLost(
    error::ContextLostReason reason) {
  // Only lose the context once.
  if (WasContextLost()) {
    return;
  }

  // Don't make GL calls in here, the context might not be current.
  command_buffer_service()->SetContextLostReason(reason);
  context_lost_ = true;
}

gpu::gles2::Logger* GLES2DecoderPassthroughImpl::GetLogger() {
  return &logger_;
}

void GLES2DecoderPassthroughImpl::BeginDecoding() {
  gpu_tracer_->BeginDecoding();
  gpu_trace_commands_ = gpu_tracer_->IsTracing() && *gpu_decoder_category_;
  gpu_debug_commands_ = log_commands() || debug() || gpu_trace_commands_;
}

void GLES2DecoderPassthroughImpl::EndDecoding() {
  gpu_tracer_->EndDecoding();
}

const gpu::gles2::ContextState* GLES2DecoderPassthroughImpl::GetContextState() {
  return nullptr;
}

scoped_refptr<ShaderTranslatorInterface>
GLES2DecoderPassthroughImpl::GetTranslator(GLenum type) {
  return nullptr;
}

void GLES2DecoderPassthroughImpl::BindImage(uint32_t client_texture_id,
                                            uint32_t texture_target,
                                            gl::GLImage* image,
                                            bool can_bind_to_sampler) {
  scoped_refptr<TexturePassthrough> passthrough_texture = nullptr;
  if (!resources_->texture_object_map.GetServiceID(client_texture_id,
                                                   &passthrough_texture)) {
    return;
  }

  DCHECK(passthrough_texture != nullptr);

  // |can_bind_to_sampler| indicates that we don't need to take any action.
  // Otherwise, we do it when the texture is first used for drawing.
  passthrough_texture->set_is_bind_pending(!can_bind_to_sampler);

  GLenum bind_target = GLES2Util::GLFaceTargetToTextureTarget(texture_target);
  if (passthrough_texture->target() != bind_target) {
    return;
  }

  // Reference the image even if it is not bound as a sampler.
  passthrough_texture->SetLevelImage(texture_target, 0, image);
}

void GLES2DecoderPassthroughImpl::BindOnePendingImage(
    GLenum target,
    TexturePassthrough* texture) {
  // It's possible that this texture was processed by some other decoder
  // while it was also bound here, or that it has been destroyed.  In
  // either case, do nothing.
  if (!texture || !texture->is_bind_pending())
    return;

  // TODO(liberato): make this work for non-0 levels.
  gl::GLImage* image = texture->GetLevelImage(target, 0);

  // Note that we might not have an image anymore, if it was unbound from
  // the texture by some other decoder while the texture was still bound
  // here.  In that case, just ignore it.
  //
  // Similarly, we might not even get here if an image was bound to a
  // texture that requries bind/copy, but that texture was already bound
  // to a sampler in this decoder.
  if (!image)
    return;

  // TODO: internalformat?
  if (!image->BindTexImage(target))
    image->CopyTexImage(target);

  // If copy / bind fail, then we could keep the bind state the same.
  // However, for now, we only try once.
  texture->set_is_bind_pending(false);

  // No client ID available here, can this texture already be discardable?
  UpdateTextureSizeFromTexturePassthrough(texture, 0);
}

void GLES2DecoderPassthroughImpl::BindPendingImagesForSamplers() {
  for (TexturePendingBinding& pending : textures_pending_binding_)
    BindOnePendingImage(pending.target, pending.texture.get());

  // Note that we clear the texures even if they fail.  We could keep
  // them around.
  textures_pending_binding_.clear();
}

void GLES2DecoderPassthroughImpl::OnDebugMessage(GLenum source,
                                                 GLenum type,
                                                 GLuint id,
                                                 GLenum severity,
                                                 GLsizei length,
                                                 const GLchar* message) {
  if (type == GL_DEBUG_TYPE_ERROR && source == GL_DEBUG_SOURCE_API) {
    had_error_callback_ = true;
  }
}

void GLES2DecoderPassthroughImpl::SetCopyTextureResourceManagerForTest(
    CopyTextureCHROMIUMResourceManager* copy_texture_resource_manager) {
  NOTIMPLEMENTED();
}

void GLES2DecoderPassthroughImpl::SetCopyTexImageBlitterForTest(
    CopyTexImageResourceManager* copy_tex_image_blit) {
  NOTIMPLEMENTED();
}

const char* GLES2DecoderPassthroughImpl::GetCommandName(
    unsigned int command_id) const {
  if (command_id >= kFirstGLES2Command && command_id < kNumCommands) {
    return gles2::GetCommandName(static_cast<CommandId>(command_id));
  }
  return GetCommonCommandName(static_cast<cmd::CommandId>(command_id));
}

void GLES2DecoderPassthroughImpl::SetOptionalExtensionsRequestedForTesting(
    bool request_extensions) {
  request_optional_extensions_ = request_extensions;
}

void* GLES2DecoderPassthroughImpl::GetScratchMemory(size_t size) {
  if (scratch_memory_.size() < size) {
    scratch_memory_.resize(size, 0);
  }
  return scratch_memory_.data();
}

template <typename T>
error::Error GLES2DecoderPassthroughImpl::PatchGetNumericResults(GLenum pname,
                                                                 GLsizei length,
                                                                 T* params) {
  // Likely a gl error if no parameters were returned
  if (length < 1) {
    return error::kNoError;
  }

  switch (pname) {
    case GL_NUM_EXTENSIONS:
      // Currently handled on the client side.
      params[0] = 0;
      break;

    case GL_TEXTURE_BINDING_2D:
    case GL_TEXTURE_BINDING_CUBE_MAP:
    case GL_TEXTURE_BINDING_2D_ARRAY:
    case GL_TEXTURE_BINDING_3D:
      if (*params != 0 &&
          !GetClientID(&resources_->texture_id_map, *params, params)) {
        return error::kInvalidArguments;
      }
      break;

    case GL_ARRAY_BUFFER_BINDING:
    case GL_ELEMENT_ARRAY_BUFFER_BINDING:
    case GL_PIXEL_PACK_BUFFER_BINDING:
    case GL_PIXEL_UNPACK_BUFFER_BINDING:
    case GL_TRANSFORM_FEEDBACK_BUFFER_BINDING:
    case GL_COPY_READ_BUFFER_BINDING:
    case GL_COPY_WRITE_BUFFER_BINDING:
    case GL_UNIFORM_BUFFER_BINDING:
      if (*params != 0 &&
          !GetClientID(&resources_->buffer_id_map, *params, params)) {
        return error::kInvalidArguments;
      }
      break;

    case GL_RENDERBUFFER_BINDING:
      if (*params != 0 &&
          !GetClientID(&resources_->renderbuffer_id_map, *params, params)) {
        return error::kInvalidArguments;
      }
      break;

    case GL_SAMPLER_BINDING:
      if (*params != 0 &&
          !GetClientID(&resources_->sampler_id_map, *params, params)) {
        return error::kInvalidArguments;
      }
      break;

    case GL_ACTIVE_PROGRAM:
      if (*params != 0 &&
          !GetClientID(&resources_->program_id_map, *params, params)) {
        return error::kInvalidArguments;
      }
      break;

    case GL_FRAMEBUFFER_BINDING:
    case GL_READ_FRAMEBUFFER_BINDING:
      if (*params != 0 && !GetClientID(&framebuffer_id_map_, *params, params)) {
        return error::kInvalidArguments;
      }
      break;

    case GL_TRANSFORM_FEEDBACK_BINDING:
      if (*params != 0 &&
          !GetClientID(&transform_feedback_id_map_, *params, params)) {
        return error::kInvalidArguments;
      }
      break;

    case GL_VERTEX_ARRAY_BINDING:
      if (*params != 0 &&
          !GetClientID(&vertex_array_id_map_, *params, params)) {
        return error::kInvalidArguments;
      }
      break;

    case GL_VIEWPORT:
      // The applied viewport and scissor could be offset by the current
      // surface, return the tracked values instead
      if (length < 4) {
        return error::kInvalidArguments;
      }
      std::copy(std::begin(viewport_), std::end(viewport_), params);
      break;

    case GL_SCISSOR_BOX:
      // The applied viewport and scissor could be offset by the current
      // surface, return the tracked values instead
      if (length < 4) {
        return error::kInvalidArguments;
      }
      std::copy(std::begin(scissor_), std::end(scissor_), params);
      break;

    default:
      break;
  }

  return error::kNoError;
}

// Instantiate templated functions
#define INSTANTIATE_PATCH_NUMERIC_RESULTS(type)                              \
  template error::Error GLES2DecoderPassthroughImpl::PatchGetNumericResults( \
      GLenum, GLsizei, type*)
INSTANTIATE_PATCH_NUMERIC_RESULTS(GLint);
INSTANTIATE_PATCH_NUMERIC_RESULTS(GLint64);
INSTANTIATE_PATCH_NUMERIC_RESULTS(GLfloat);
INSTANTIATE_PATCH_NUMERIC_RESULTS(GLboolean);
#undef INSTANTIATE_PATCH_NUMERIC_RESULTS

template <typename T>
error::Error GLES2DecoderPassthroughImpl::PatchGetBufferResults(GLenum target,
                                                                GLenum pname,
                                                                GLsizei bufsize,
                                                                GLsizei* length,
                                                                T* params) {
  if (pname != GL_BUFFER_ACCESS_FLAGS) {
    return error::kNoError;
  }

  // If there was no error, the buffer target should exist
  DCHECK(bound_buffers_.find(target) != bound_buffers_.end());
  GLuint current_client_buffer = bound_buffers_[target];

  auto mapped_buffer_info_iter =
      resources_->mapped_buffer_map.find(current_client_buffer);
  if (mapped_buffer_info_iter == resources_->mapped_buffer_map.end()) {
    // Buffer is not mapped, nothing to do
    return error::kNoError;
  }

  // Buffer is mapped, patch the result with the original access flags
  DCHECK_GE(bufsize, 1);
  DCHECK_EQ(*length, 1);
  params[0] = mapped_buffer_info_iter->second.original_access;
  return error::kNoError;
}

template error::Error GLES2DecoderPassthroughImpl::PatchGetBufferResults(
    GLenum target,
    GLenum pname,
    GLsizei bufsize,
    GLsizei* length,
    GLint64* params);
template error::Error GLES2DecoderPassthroughImpl::PatchGetBufferResults(
    GLenum target,
    GLenum pname,
    GLsizei bufsize,
    GLsizei* length,
    GLint* params);

error::Error
GLES2DecoderPassthroughImpl::PatchGetFramebufferAttachmentParameter(
    GLenum target,
    GLenum attachment,
    GLenum pname,
    GLsizei length,
    GLint* params) {
  // Likely a gl error if no parameters were returned
  if (length < 1) {
    return error::kNoError;
  }

  switch (pname) {
    // If the attached object name was requested, it needs to be converted back
    // to a client id.
    case GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME: {
      GLint object_type = GL_NONE;
      api()->glGetFramebufferAttachmentParameterivEXTFn(
          target, attachment, GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE,
          &object_type);

      switch (object_type) {
        case GL_TEXTURE:
          if (!GetClientID(&resources_->texture_id_map, *params, params)) {
            return error::kInvalidArguments;
          }
          break;

        case GL_RENDERBUFFER:
          if (!GetClientID(&resources_->renderbuffer_id_map, *params, params)) {
            return error::kInvalidArguments;
          }
          break;

        case GL_NONE:
          // Default framebuffer, don't transform the result
          break;

        default:
          NOTREACHED();
          break;
      }
    } break;

    // If the framebuffer is an emulated default framebuffer, all attachment
    // object types are GL_FRAMEBUFFER_DEFAULT
    case GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE:
      if (IsEmulatedFramebufferBound(target)) {
        *params = GL_FRAMEBUFFER_DEFAULT;
      }
      break;

    default:
      break;
  }

  return error::kNoError;
}

void GLES2DecoderPassthroughImpl::InsertError(GLenum error,
                                              const std::string& message) {
  errors_.insert(error);
  LogGLDebugMessage(GL_DEBUG_SOURCE_API, GL_DEBUG_TYPE_ERROR, error,
                    GL_DEBUG_SEVERITY_HIGH, message.length(), message.c_str(),
                    GetLogger());
}

GLenum GLES2DecoderPassthroughImpl::PopError() {
  GLenum error = GL_NO_ERROR;
  if (!errors_.empty()) {
    error = *errors_.begin();
    errors_.erase(errors_.begin());
  }
  return error;
}

bool GLES2DecoderPassthroughImpl::FlushErrors() {
  bool had_error = false;
  GLenum error = glGetError();
  while (error != GL_NO_ERROR) {
    errors_.insert(error);
    had_error = true;

    // Check for context loss on out-of-memory errors
    if (error == GL_OUT_OF_MEMORY && !WasContextLost() &&
        lose_context_when_out_of_memory_) {
      error::ContextLostReason other = error::kOutOfMemory;
      if (CheckResetStatus()) {
        other = error::kUnknown;
      } else {
        // Need to lose current context before broadcasting!
        MarkContextLost(error::kOutOfMemory);
      }
      group_->LoseContexts(other);
      break;
    }

    error = glGetError();
  }
  return had_error;
}

bool GLES2DecoderPassthroughImpl::CheckResetStatus() {
  DCHECK(!WasContextLost());
  DCHECK(context_->IsCurrent(nullptr));

  if (IsRobustnessSupported()) {
    // If the reason for the call was a GL error, we can try to determine the
    // reset status more accurately.
    GLenum driver_status = api()->glGetGraphicsResetStatusARBFn();
    if (driver_status == GL_NO_ERROR) {
      return false;
    }

    switch (driver_status) {
      case GL_GUILTY_CONTEXT_RESET_ARB:
        MarkContextLost(error::kGuilty);
        break;
      case GL_INNOCENT_CONTEXT_RESET_ARB:
        MarkContextLost(error::kInnocent);
        break;
      case GL_UNKNOWN_CONTEXT_RESET_ARB:
        MarkContextLost(error::kUnknown);
        break;
      default:
        NOTREACHED();
        return false;
    }
    reset_by_robustness_extension_ = true;
    return true;
  }
  return false;
}

bool GLES2DecoderPassthroughImpl::IsRobustnessSupported() {
  return has_robustness_extension_ &&
         context_->WasAllocatedUsingRobustnessExtension();
}

bool GLES2DecoderPassthroughImpl::IsEmulatedQueryTarget(GLenum target) const {
  switch (target) {
    case GL_COMMANDS_COMPLETED_CHROMIUM:
    case GL_READBACK_SHADOW_COPIES_UPDATED_CHROMIUM:
    case GL_COMMANDS_ISSUED_CHROMIUM:
    case GL_LATENCY_QUERY_CHROMIUM:
    case GL_ASYNC_PIXEL_PACK_COMPLETED_CHROMIUM:
    case GL_GET_ERROR_QUERY_CHROMIUM:
      return true;

    default:
      return false;
  }
}

error::Error GLES2DecoderPassthroughImpl::ProcessQueries(bool did_finish) {
  while (!pending_queries_.empty()) {
    const PendingQuery& query = pending_queries_.front();
    GLuint result_available = GL_FALSE;
    GLuint64 result = 0;
    switch (query.target) {
      case GL_COMMANDS_COMPLETED_CHROMIUM:
        DCHECK(query.commands_completed_fence != nullptr);
        // Note: |did_finish| guarantees that the GPU has passed the fence but
        // we cannot assume that GLFence::HasCompleted() will return true yet as
        // that's not guaranteed by all GLFence implementations.
        result_available =
            did_finish || query.commands_completed_fence->HasCompleted();
        result = result_available;
        break;

      case GL_COMMANDS_ISSUED_CHROMIUM:
        result_available = GL_TRUE;
        result = GL_TRUE;
        break;

      case GL_LATENCY_QUERY_CHROMIUM:
        result_available = GL_TRUE;
        // TODO: time from when the query is ended?
        result = (base::TimeTicks::Now() - base::TimeTicks()).InMilliseconds();
        break;

      case GL_ASYNC_PIXEL_PACK_COMPLETED_CHROMIUM:
        // Initialize the result to being available.  Will be marked as
        // unavailable if any pending read pixels operations reference this
        // query.
        result_available = GL_TRUE;
        result = GL_TRUE;
        for (const PendingReadPixels& pending_read_pixels :
             pending_read_pixels_) {
          if (pending_read_pixels.waiting_async_pack_queries.count(
                  query.service_id) > 0) {
            // Async read pixel processing happens before query processing. If
            // there was a finish then there should be no pending read pixels.
            DCHECK(!did_finish);
            result_available = GL_FALSE;
            result = GL_FALSE;
            break;
          }
        }
        break;

      case GL_READBACK_SHADOW_COPIES_UPDATED_CHROMIUM:
        DCHECK(query.buffer_shadow_update_fence);
        if (did_finish || query.buffer_shadow_update_fence->HasCompleted()) {
          ReadBackBuffersIntoShadowCopies(query.buffer_shadow_updates);
          result_available = GL_TRUE;
          result = 0;
        }
        break;

      case GL_GET_ERROR_QUERY_CHROMIUM:
        result_available = GL_TRUE;
        FlushErrors();
        result = PopError();
        break;

      default:
        DCHECK(!IsEmulatedQueryTarget(query.target));
        if (did_finish) {
          result_available = GL_TRUE;
        } else {
          api()->glGetQueryObjectuivFn(
              query.service_id, GL_QUERY_RESULT_AVAILABLE, &result_available);
        }
        if (result_available == GL_TRUE) {
          if (feature_info_->feature_flags().ext_disjoint_timer_query) {
            api()->glGetQueryObjectui64vFn(query.service_id, GL_QUERY_RESULT,
                                           &result);
          } else {
            GLuint temp_result = 0;
            api()->glGetQueryObjectuivFn(query.service_id, GL_QUERY_RESULT,
                                         &temp_result);
            result = temp_result;
          }
        }
        break;
    }

    if (!result_available) {
      break;
    }

    // Mark the query as complete
    query.sync->result = result;
    base::subtle::Release_Store(&query.sync->process_count, query.submit_count);
    pending_queries_.pop_front();
  }

  // If api()->glFinishFn() has been called, all of our queries should be
  // completed.
  DCHECK(!did_finish || pending_queries_.empty());
  return error::kNoError;
}

void GLES2DecoderPassthroughImpl::RemovePendingQuery(GLuint service_id) {
  auto pending_iter =
      std::find_if(pending_queries_.begin(), pending_queries_.end(),
                   [service_id](const PendingQuery& pending_query) {
                     return pending_query.service_id == service_id;
                   });
  if (pending_iter != pending_queries_.end()) {
    QuerySync* sync = pending_iter->sync;
    sync->result = 0;
    base::subtle::Release_Store(&sync->process_count,
                                pending_iter->submit_count);

    pending_queries_.erase(pending_iter);
  }
}

void GLES2DecoderPassthroughImpl::ReadBackBuffersIntoShadowCopies(
    const BufferShadowUpdateMap& updates) {
  GLint old_binding = 0;
  api()->glGetIntegervFn(GL_ARRAY_BUFFER_BINDING, &old_binding);
  for (const auto& u : updates) {
    GLuint service_id = u.first;
    const auto& update = u.second;

    void* shadow = update.shm->GetDataAddress(update.shm_offset, update.size);
    DCHECK(shadow);

    api()->glBindBufferFn(GL_ARRAY_BUFFER, service_id);
    GLint already_mapped = GL_TRUE;
    api()->glGetBufferParameterivFn(GL_ARRAY_BUFFER, GL_BUFFER_MAPPED,
                                    &already_mapped);
    if (already_mapped) {
      // The buffer is already mapped by the client. It's okay that the shadow
      // copy will be out-of-date, because the client will never read it:
      // * Client issues READBACK_SHADOW_COPIES_UPDATED_CHROMIUM query
      // * Client maps buffer
      // * Client receives signal that the query completed
      // * Client unmaps buffer - invalidating the shadow copy
      // * Client maps buffer to read back - hits the round-trip path
      continue;
    }

    void* mapped = api()->glMapBufferRangeFn(GL_ARRAY_BUFFER, 0, update.size,
                                             GL_MAP_READ_BIT);
    if (!mapped) {
      DLOG(ERROR) << "glMapBufferRange unexpectedly returned NULL";
      MarkContextLost(error::kOutOfMemory);
      group_->LoseContexts(error::kUnknown);
      return;
    }
    memcpy(shadow, mapped, update.size);
    bool unmap_ok = api()->glUnmapBufferFn(GL_ARRAY_BUFFER);
    if (unmap_ok == GL_FALSE) {
      DLOG(ERROR) << "glUnmapBuffer unexpectedly returned GL_FALSE";
      MarkContextLost(error::kUnknown);
      group_->LoseContexts(error::kUnknown);
      return;
    }
  }

  // Restore original GL_ARRAY_BUFFER binding
  api()->glBindBufferFn(GL_ARRAY_BUFFER, old_binding);
}

error::Error GLES2DecoderPassthroughImpl::ProcessReadPixels(bool did_finish) {
  while (!pending_read_pixels_.empty()) {
    const PendingReadPixels& pending_read_pixels = pending_read_pixels_.front();
    if (did_finish || pending_read_pixels.fence->HasCompleted()) {
      using Result = cmds::ReadPixels::Result;
      Result* result = nullptr;
      if (pending_read_pixels.result_shm_id != 0) {
        result = GetSharedMemoryAs<Result*>(
            pending_read_pixels.result_shm_id,
            pending_read_pixels.result_shm_offset, sizeof(*result));
        if (!result) {
          api()->glDeleteBuffersARBFn(1,
                                      &pending_read_pixels.buffer_service_id);
          pending_read_pixels_.pop_front();
          break;
        }
      }

      void* pixels =
          GetSharedMemoryAs<void*>(pending_read_pixels.pixels_shm_id,
                                   pending_read_pixels.pixels_shm_offset,
                                   pending_read_pixels.pixels_size);
      if (!pixels) {
        api()->glDeleteBuffersARBFn(1, &pending_read_pixels.buffer_service_id);
        pending_read_pixels_.pop_front();
        break;
      }

      api()->glBindBufferFn(GL_PIXEL_PACK_BUFFER_ARB,
                            pending_read_pixels.buffer_service_id);
      void* data = nullptr;
      if (feature_info_->feature_flags().map_buffer_range) {
        data = api()->glMapBufferRangeFn(GL_PIXEL_PACK_BUFFER_ARB, 0,
                                         pending_read_pixels.pixels_size,
                                         GL_MAP_READ_BIT);
      } else {
        data = api()->glMapBufferFn(GL_PIXEL_PACK_BUFFER_ARB, GL_READ_ONLY);
      }
      if (!data) {
        InsertError(GL_OUT_OF_MEMORY, "Failed to map pixel pack buffer.");
        pending_read_pixels_.pop_front();
        break;
      }

      memcpy(pixels, data, pending_read_pixels.pixels_size);
      api()->glUnmapBufferFn(GL_PIXEL_PACK_BUFFER_ARB);
      api()->glBindBufferFn(GL_PIXEL_PACK_BUFFER_ARB,
                            resources_->buffer_id_map.GetServiceIDOrInvalid(
                                bound_buffers_[GL_PIXEL_PACK_BUFFER_ARB]));
      api()->glDeleteBuffersARBFn(1, &pending_read_pixels.buffer_service_id);

      if (result != nullptr) {
        result->success = 1;
      }

      pending_read_pixels_.pop_front();
    }
  }

  // If api()->glFinishFn() has been called, all of our fences should be
  // completed.
  DCHECK(!did_finish || pending_read_pixels_.empty());
  return error::kNoError;
}

void GLES2DecoderPassthroughImpl::ProcessDescheduleUntilFinished() {
  if (deschedule_until_finished_fences_.size() < 2) {
    return;
  }
  DCHECK_EQ(2u, deschedule_until_finished_fences_.size());

  if (!deschedule_until_finished_fences_[0]->HasCompleted()) {
    return;
  }

  TRACE_EVENT_ASYNC_END0(
      "cc", "GLES2DecoderPassthroughImpl::DescheduleUntilFinished", this);
  deschedule_until_finished_fences_.erase(
      deschedule_until_finished_fences_.begin());
  client_->OnRescheduleAfterFinished();
}

void GLES2DecoderPassthroughImpl::UpdateTextureBinding(
    GLenum target,
    GLuint client_id,
    TexturePassthrough* texture) {
  GLuint texture_service_id = texture ? texture->service_id() : 0;
  size_t cur_texture_unit = active_texture_unit_;
  auto& target_bound_textures =
      bound_textures_[static_cast<size_t>(GLenumToTextureTarget(target))];
  for (size_t bound_texture_index = 0;
       bound_texture_index < target_bound_textures.size();
       bound_texture_index++) {
    if (target_bound_textures[bound_texture_index].client_id == client_id) {
      // Update the active texture unit if needed
      if (bound_texture_index != cur_texture_unit) {
        api()->glActiveTextureFn(
            static_cast<GLenum>(GL_TEXTURE0 + bound_texture_index));
        cur_texture_unit = bound_texture_index;
      }

      // Update the texture binding
      api()->glBindTextureFn(target, texture_service_id);
      target_bound_textures[bound_texture_index].texture = texture;
    }
  }

  // Reset the active texture unit if it was changed
  if (cur_texture_unit != active_texture_unit_) {
    api()->glActiveTextureFn(
        static_cast<GLenum>(GL_TEXTURE0 + active_texture_unit_));
  }
}

void GLES2DecoderPassthroughImpl::UpdateTextureSizeFromTexturePassthrough(
    TexturePassthrough* texture,
    GLuint client_id) {
  if (texture == nullptr) {
    return;
  }

  CheckErrorCallbackState();

  GLenum target = texture->target();
  TextureTarget internal_texture_type = GLenumToTextureTarget(target);
  BoundTexture& bound_texture =
      bound_textures_[static_cast<size_t>(internal_texture_type)]
                     [active_texture_unit_];
  bool needs_rebind = bound_texture.texture == texture;
  if (needs_rebind) {
    glBindTexture(target, texture->service_id());
  }

  UpdateBoundTexturePassthroughSize(api(), texture);

  // If a client ID is available, notify the discardable manager of the size
  // change
  if (client_id != 0) {
    group_->passthrough_discardable_manager()->UpdateTextureSize(
        client_id, group_.get(), texture->estimated_size());
  }

  if (needs_rebind) {
    GLuint old_texture =
        bound_texture.texture ? bound_texture.texture->service_id() : 0;
    glBindTexture(target, old_texture);
  }

  DCHECK(!CheckErrorCallbackState());
}

void GLES2DecoderPassthroughImpl::UpdateTextureSizeFromTarget(GLenum target) {
  GLenum texture_type = TextureTargetToTextureType(target);
  TextureTarget internal_texture_type = GLenumToTextureTarget(texture_type);
  DCHECK(internal_texture_type != TextureTarget::kUnkown);
  BoundTexture& bound_texture =
      bound_textures_[static_cast<size_t>(internal_texture_type)]
                     [active_texture_unit_];
  UpdateTextureSizeFromTexturePassthrough(bound_texture.texture.get(),
                                          bound_texture.client_id);
}

void GLES2DecoderPassthroughImpl::UpdateTextureSizeFromClientID(
    GLuint client_id) {
  scoped_refptr<TexturePassthrough> texture = nullptr;
  if (resources_->texture_object_map.GetServiceID(client_id, &texture)) {
    UpdateTextureSizeFromTexturePassthrough(texture.get(), client_id);
  }
}

error::Error GLES2DecoderPassthroughImpl::HandleSetActiveURLCHROMIUM(
    uint32_t immediate_data_size,
    const volatile void* cmd_data) {
  const volatile cmds::SetActiveURLCHROMIUM& c =
      *static_cast<const volatile cmds::SetActiveURLCHROMIUM*>(cmd_data);
  Bucket* url_bucket = GetBucket(c.url_bucket_id);
  static constexpr size_t kMaxStrLen = 1024;
  if (!url_bucket || url_bucket->size() == 0 ||
      url_bucket->size() > kMaxStrLen + 1) {
    return error::kInvalidArguments;
  }

  size_t size = url_bucket->size() - 1;
  const char* url_str = url_bucket->GetDataAs<const char*>(0, size);
  if (!url_str)
    return error::kInvalidArguments;

  GURL url(base::StringPiece(url_str, size));
  client_->SetActiveURL(std::move(url));
  return error::kNoError;
}

error::Error GLES2DecoderPassthroughImpl::BindTexImage2DCHROMIUMImpl(
    GLenum target,
    GLenum internalformat,
    GLint imageId) {
  if (target != GL_TEXTURE_2D) {
    InsertError(GL_INVALID_ENUM, "Invalid target");
    return error::kNoError;
  }

  gl::GLImage* image = group_->image_manager()->LookupImage(imageId);
  if (image == nullptr) {
    InsertError(GL_INVALID_OPERATION, "No image found with the given ID");
    return error::kNoError;
  }

  const BoundTexture& bound_texture =
      bound_textures_[static_cast<size_t>(TextureTarget::k2D)]
                     [active_texture_unit_];
  if (bound_texture.texture == nullptr) {
    InsertError(GL_INVALID_OPERATION, "No texture bound");
    return error::kNoError;
  }

  if (internalformat) {
    if (!image->BindTexImageWithInternalformat(target, internalformat)) {
      image->CopyTexImage(target);
    }
  } else {
    if (!image->BindTexImage(target)) {
      image->CopyTexImage(target);
    }
  }

  // Target is already validated
  UpdateTextureSizeFromTarget(target);

  DCHECK(bound_texture.texture != nullptr);
  bound_texture.texture->SetLevelImage(target, 0, image);

  // If there was any GLImage bound to |target| on this texture unit, then
  // forget it.
  RemovePendingBindingTexture(target, active_texture_unit_);

  return error::kNoError;
}

void GLES2DecoderPassthroughImpl::VerifyServiceTextureObjectsExist() {
  resources_->texture_object_map.ForEach(
      [this](GLuint client_id, scoped_refptr<TexturePassthrough> texture) {
        DCHECK_EQ(GL_TRUE, api()->glIsTextureFn(texture->service_id()));
      });
}

bool GLES2DecoderPassthroughImpl::IsEmulatedFramebufferBound(
    GLenum target) const {
  if (!emulated_back_buffer_) {
    return false;
  }

  if ((target == GL_FRAMEBUFFER_EXT || target == GL_DRAW_FRAMEBUFFER) &&
      bound_draw_framebuffer_ == 0) {
    return true;
  }

  if (target == GL_READ_FRAMEBUFFER && bound_read_framebuffer_ == 0) {
    return true;
  }

  return false;
}

error::Error GLES2DecoderPassthroughImpl::CheckSwapBuffersResult(
    gfx::SwapResult result,
    const char* function_name) {
  if (result == gfx::SwapResult::SWAP_FAILED) {
    LOG(ERROR) << "Context lost because " << function_name << " failed.";
    if (!CheckResetStatus()) {
      MarkContextLost(error::kUnknown);
      group_->LoseContexts(error::kUnknown);
      return error::kLostContext;
    }
  }

  return error::kNoError;
}

// static
GLES2DecoderPassthroughImpl::TextureTarget
GLES2DecoderPassthroughImpl::GLenumToTextureTarget(GLenum target) {
  switch (target) {
    case GL_TEXTURE_2D:
      return TextureTarget::k2D;
    case GL_TEXTURE_CUBE_MAP:
      return TextureTarget::kCubeMap;
    case GL_TEXTURE_2D_ARRAY:
      return TextureTarget::k2DArray;
    case GL_TEXTURE_3D:
      return TextureTarget::k3D;
    case GL_TEXTURE_2D_MULTISAMPLE:
      return TextureTarget::k2DMultisample;
    case GL_TEXTURE_EXTERNAL_OES:
      return TextureTarget::kExternal;
    case GL_TEXTURE_RECTANGLE_ARB:
      return TextureTarget::kRectangle;
    default:
      return TextureTarget::kUnkown;
  }
}

gfx::Vector2d GLES2DecoderPassthroughImpl::GetSurfaceDrawOffset() const {
  if (bound_draw_framebuffer_ != 0 || offscreen_) {
    return gfx::Vector2d();
  }
  return surface_->GetDrawOffset();
}

void GLES2DecoderPassthroughImpl::ApplySurfaceDrawOffset() {
  if (offscreen_ || !surface_->SupportsDCLayers()) {
    return;
  }

  gfx::Vector2d framebuffer_offset = GetSurfaceDrawOffset();
  api()->glViewportFn(viewport_[0] + framebuffer_offset.x(),
                      viewport_[1] + framebuffer_offset.y(), viewport_[2],
                      viewport_[3]);
  api()->glScissorFn(scissor_[0] + framebuffer_offset.x(),
                     scissor_[1] + framebuffer_offset.y(), scissor_[2],
                     scissor_[3]);
}

bool GLES2DecoderPassthroughImpl::CheckErrorCallbackState() {
  bool had_error_ = had_error_callback_;
  had_error_callback_ = false;
  if (had_error_) {
    // Make sure lose-context-on-OOM logic is triggered as early as possible.
    FlushErrors();
  }
  return had_error_;
}

#define GLES2_CMD_OP(name)                                               \
  {                                                                      \
      &GLES2DecoderPassthroughImpl::Handle##name, cmds::name::kArgFlags, \
      cmds::name::cmd_flags,                                             \
      sizeof(cmds::name) / sizeof(CommandBufferEntry) - 1,               \
  }, /* NOLINT */

constexpr GLES2DecoderPassthroughImpl::CommandInfo
    GLES2DecoderPassthroughImpl::command_info[] = {
        GLES2_COMMAND_LIST(GLES2_CMD_OP)};

#undef GLES2_CMD_OP

}  // namespace gles2
}  // namespace gpu