components/surface_embed/browser/surface_embed_host.cc

// Copyright 2026 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/surface_embed/browser/surface_embed_host.h"

#include <algorithm>
#include <optional>

#include "base/check.h"
#include "base/functional/bind.h"
#include "base/memory/ptr_util.h"
#include "components/surface_embed/browser/surface_embed_handle.h"
#include "components/viz/common/surfaces/frame_sink_id.h"
#include "content/public/browser/document_user_data.h"
#include "content/public/browser/render_frame_host.h"
#include "content/public/browser/surface_embed_connector.h"
#include "content/public/browser/web_contents.h"
#include "mojo/public/cpp/bindings/message.h"
#include "third_party/abseil-cpp/absl/container/flat_hash_set.h"
#include "third_party/blink/public/common/frame/frame_visual_properties.h"
#include "ui/accessibility/ax_node_id_forward.h"
#include "ui/accessibility/ax_tree_id.h"

namespace surface_embed {

// Owns all the SurfaceEmbedHost instances for a given document.
class SurfaceEmbedHostCollection
    : public content::DocumentUserData<SurfaceEmbedHostCollection> {
 public:
  ~SurfaceEmbedHostCollection() override;

  SurfaceEmbedHostCollection(const SurfaceEmbedHostCollection&) = delete;
  SurfaceEmbedHostCollection& operator=(const SurfaceEmbedHostCollection&) =
      delete;

  // Creates a new SurfaceEmbedHost and adds it to this collection.
  SurfaceEmbedHost* CreateHost();
  void RemoveHost(SurfaceEmbedHost* host);

 private:
  friend class content::DocumentUserData<SurfaceEmbedHostCollection>;

  explicit SurfaceEmbedHostCollection(content::RenderFrameHost* rfh);

  absl::flat_hash_set<std::unique_ptr<SurfaceEmbedHost>> hosts_;

  DOCUMENT_USER_DATA_KEY_DECL();
};

DOCUMENT_USER_DATA_KEY_IMPL(SurfaceEmbedHostCollection);

SurfaceEmbedHostCollection::SurfaceEmbedHostCollection(
    content::RenderFrameHost* rfh)
    : DocumentUserData<SurfaceEmbedHostCollection>(rfh) {}

SurfaceEmbedHostCollection::~SurfaceEmbedHostCollection() = default;

SurfaceEmbedHost* SurfaceEmbedHostCollection::CreateHost() {
  auto host = base::WrapUnique(new SurfaceEmbedHost(this));
  SurfaceEmbedHost* host_ptr = host.get();
  hosts_.insert(std::move(host));
  return host_ptr;
}

void SurfaceEmbedHostCollection::RemoveHost(SurfaceEmbedHost* host) {
  auto it = hosts_.find(host);
  CHECK(it != hosts_.end());
  hosts_.erase(it);
}

// static
SurfaceEmbedHost* SurfaceEmbedHost::Create(
    content::RenderFrameHost* rfh,
    mojo::PendingAssociatedReceiver<mojom::SurfaceEmbedHost> receiver) {
  auto* collection =
      SurfaceEmbedHostCollection::GetOrCreateForCurrentDocument(rfh);
  SurfaceEmbedHost* host = collection->CreateHost();
  host->Bind(std::move(receiver));
  return host;
}

SurfaceEmbedHost::SurfaceEmbedHost(SurfaceEmbedHostCollection* collection)
    : collection_(*collection) {}

SurfaceEmbedHost::~SurfaceEmbedHost() {
  DetachConnector();
  if (destruction_callback_for_testing_) {
    std::move(destruction_callback_for_testing_).Run();
  }
}

void SurfaceEmbedHost::Bind(
    mojo::PendingAssociatedReceiver<mojom::SurfaceEmbedHost> receiver) {
  CHECK(!receiver_.is_bound());
  receiver_.Bind(std::move(receiver));
  receiver_.set_disconnect_handler(base::BindOnce(
      &SurfaceEmbedHost::OnMojoDisconnect, base::Unretained(this)));
}

void SurfaceEmbedHost::SetDestructionCallbackForTesting(
    base::OnceClosure callback) {
  destruction_callback_for_testing_ = std::move(callback);
}

void SurfaceEmbedHost::SetSurfaceEmbed(
    mojo::PendingAssociatedRemote<mojom::SurfaceEmbed> surface_embed) {
  CHECK(!surface_embed_.is_bound());
  surface_embed_.Bind(std::move(surface_embed));
  surface_embed_.set_disconnect_handler(base::BindOnce(
      &SurfaceEmbedHost::OnMojoDisconnect, base::Unretained(this)));
}

void SurfaceEmbedHost::AttachConnector(const base::UnguessableToken& content_id,
                                       bool is_embed_element_focused,
                                       bool allow_pinch_zoom) {
  has_received_attach_connector_for_testing_ = true;

  // Should never call attach without having a valid SurfaceEmbed remote already
  // bound.
  CHECK(surface_embed_);

  CHECK(!content_id.is_empty());

  // If this host already has a child attached, we need to detach it first. Note
  // that this request comes from the parent side, so we don't notify the
  // SurfaceEmbed as it initiated the detachment.
  DetachConnector();

  SurfaceEmbedHandle* handle = SurfaceEmbedHandle::FromID(content_id);
  if (!handle) {
    // The child may have been destroyed while the renderer was asynchronously
    // creating the embed element.
    return;
  }

  content::WebContents* web_contents_to_attach = handle->web_contents();
  CHECK(web_contents_to_attach);

  // If the child WebContents is already attached to a SurfaceEmbedConnector, we
  // need to detach it first. Since we're detaching some other SurfaceEmbedHost,
  // we need to notify it of the detachment so the host and
  // SurfaceEmbedWebPlugin stay in sync.
  if (auto* connector = web_contents_to_attach->GetSurfaceEmbedConnector()) {
    connector->GetDelegate()->DetachedByHost();
    CHECK(!web_contents_to_attach->GetSurfaceEmbedConnector());
  }

  if (web_contents_to_attach->IsCrashed()) {
    // The child process may have crashed before the renderer for the parent
    // got the chance to attach it. We want to handle this early since attaching
    // the connector will make WebContents think the process is alive.
    surface_embed_->ChildProcessGone();
    return;
  }

  child_contents_ = web_contents_to_attach->GetWeakPtr();
  const auto pinch_gesture_mode =
      allow_pinch_zoom ? content::SurfaceEmbedConnector::PinchGestureMode::
                             kScaleChildWebContents
                       : content::SurfaceEmbedConnector::PinchGestureMode::
                             kDelegateToParentWebContents;
  content::SurfaceEmbedConnector::Attach(web_contents_to_attach,
                                         &collection_->render_frame_host(),
                                         this, pinch_gesture_mode);

  // If accessibility info was received before the connector was attached,
  // pass it to the connector now.
  if (container_accessibility_node_id_ != ui::kInvalidAXNodeID) {
    ForwardParentAccessibilityInfo();
  }

  if (is_embed_element_focused) {
    FocusChildWebContents();
  }
}

void SurfaceEmbedHost::SetAllowPinchZoom(bool allow_pinch_zoom) {
  content::SurfaceEmbedConnector* connector = GetConnector();
  if (!connector) {
    return;
  }
  connector->SetPinchGestureMode(
      allow_pinch_zoom ? content::SurfaceEmbedConnector::PinchGestureMode::
                             kScaleChildWebContents
                       : content::SurfaceEmbedConnector::PinchGestureMode::
                             kDelegateToParentWebContents);
}

void SurfaceEmbedHost::FocusChildWebContents() {
  if (child_contents_ && !child_contents_->ContainsOrIsFocusedWebContents()) {
    child_contents_->Focus();
  }
}

void SurfaceEmbedHost::DetachConnector() {
  if (GetConnector()) {
    content::SurfaceEmbedConnector::Detach(child_contents_.get());
    child_contents_ = nullptr;
  }
}

void SurfaceEmbedHost::SynchronizeVisualProperties(
    const blink::FrameVisualProperties& visual_properties,
    bool is_visible) {
  CHECK(surface_embed_.is_bound());

  if (content::SurfaceEmbedConnector* connector = GetConnector()) {
    connector->OnVisibilityChanged(
        is_visible ? blink::mojom::FrameVisibility::kRenderedInViewport
                   : blink::mojom::FrameVisibility::kNotRendered);
    connector->OnSynchronizeVisualProperties(visual_properties);
  }
}

void SurfaceEmbedHost::OnEmbedElementFocused(
    bool focused,
    blink::mojom::FocusType focus_type) {
  if (!child_contents_) {
    return;
  }

  if (!focused) {
    // TODO(crbug.com/508638062): the <embed> element in the parent frame lost
    // focus. Should we remove the page focus from the embedded page?
    return;
  }

  // When a child embed requests focus via RequestFocusOnEmbedElement(),
  // focusing the <embed> element in the parent renderer triggers
  // OnEmbedElementFocused(). In a multi-level embedding setup
  // (e.g., root -> parent embed -> child embed), clicking on the child embed
  // focuses the parent <embed> element. If there is a pending
  // RequestFocusOnEmbedElement(), do nothing so we don't call Focus() on the
  // parent <embed>'s WebContents.
  if (pending_request_focus_on_embed_element_) {
    return;
  }

  // A page-focus event is fired for the active element when the window receives
  // OS focus and the page becomes focused. It does not indicate that the
  // focused element changed.
  if (focus_type == blink::mojom::FocusType::kPage) {
    return;
  }

  if (focus_type == blink::mojom::FocusType::kForward) {
    child_contents_->FocusThroughTabTraversal(/*reverse=*/false);
  } else if (focus_type == blink::mojom::FocusType::kBackward) {
    child_contents_->FocusThroughTabTraversal(/*reverse=*/true);
  }

  FocusChildWebContents();
}

void SurfaceEmbedHost::OnEmbedElementThrottlingStatusChanged(
    mojom::RenderThrottlingStatusPtr status) {
  if (content::SurfaceEmbedConnector* connector = GetConnector()) {
    connector->UpdateRenderThrottlingStatus(status->is_throttled,
                                            status->subtree_throttled,
                                            status->display_locked);
  }
}

void SurfaceEmbedHost::SetParentAccessibilityInfo(ui::AXNodeID ax_node_id) {
  if (!ui::IsValidAXNodeIDFromRenderer(ax_node_id)) {
    mojo::ReportBadMessage("Invalid AXNodeID in SetParentAccessibilityInfo.");
    return;
  }

  container_accessibility_node_id_ = ax_node_id;

  ForwardParentAccessibilityInfo();
}

void SurfaceEmbedHost::ForwardParentAccessibilityInfo() {
  content::SurfaceEmbedConnector* connector = GetConnector();
  if (!connector) {
    return;
  }
  ui::AXTreeID ax_tree_id = collection_->render_frame_host().GetAXTreeID();
  if (ax_tree_id == ui::AXTreeIDUnknown()) {
    return;
  }
  connector->SetParentAccessibilityInfo(container_accessibility_node_id_,
                                        ax_tree_id);
}

void SurfaceEmbedHost::SetFrameSinkId(const viz::FrameSinkId& frame_sink_id,
                                      bool allow_paint_holding) {
  if (surface_embed_) {
    surface_embed_->SetFrameSinkId(frame_sink_id, allow_paint_holding);
  }
}

void SurfaceEmbedHost::UpdateLocalSurfaceIdFromChild(
    const viz::LocalSurfaceId& local_surface_id) {
  if (surface_embed_) {
    surface_embed_->UpdateLocalSurfaceIdFromChild(local_surface_id);
  }
}

void SurfaceEmbedHost::ChildProcessGone() {
  if (surface_embed_) {
    surface_embed_->ChildProcessGone();
  }
}

void SurfaceEmbedHost::DetachedByHost() {
  // We're being forcibly detached (child being re-attached elsewhere).
  CHECK(child_contents_);

  // TODO(surface-embed): Notify the renderer's SurfaceEmbedWebPlugin that the
  // host initiated the detachment.

  DetachConnector();
}

void SurfaceEmbedHost::RequestFocusOnEmbedElement() {
  if (pending_request_focus_on_embed_element_) {
    return;
  }

  if (surface_embed_) {
    pending_request_focus_on_embed_element_ = true;
    surface_embed_->RequestFocusOnEmbedElement(
        base::BindOnce(&SurfaceEmbedHost::OnRequestFocusOnEmbedElementCompleted,
                       weak_ptr_factory_.GetWeakPtr()));
  }
}

void SurfaceEmbedHost::OnRequestFocusOnEmbedElementCompleted() {
  CHECK(pending_request_focus_on_embed_element_);
  pending_request_focus_on_embed_element_ = false;
}

void SurfaceEmbedHost::AdvanceFocusFromEmbedElement(bool reverse) {
  if (surface_embed_) {
    surface_embed_->AdvanceFocusFromEmbedElement(reverse);
  }
}

bool SurfaceEmbedHost::IsAttachedForTesting() const {
  return child_contents_ != nullptr;
}

void SurfaceEmbedHost::OnMojoDisconnect() {
  // Reset both pipes. This will prevent the other disconnect handler from being
  // called if it was also scheduled to run. The first one wins.
  receiver_.reset();
  surface_embed_.reset();
  collection_->RemoveHost(this);
}

content::SurfaceEmbedConnector* SurfaceEmbedHost::GetConnector() const {
  return child_contents_ ? child_contents_->GetSurfaceEmbedConnector()
                         : nullptr;
}

}  // namespace surface_embed