cc/base/features.h

// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CC_BASE_FEATURES_H_
#define CC_BASE_FEATURES_H_

#include "base/feature_list.h"
#include "build/build_config.h"
#include "cc/base/base_export.h"

namespace features {

CC_BASE_EXPORT BASE_DECLARE_FEATURE(kAnimatedImageResume);
CC_BASE_EXPORT extern bool IsImpulseScrollAnimationEnabled();
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kSynchronizedScrolling);

// Elastic overscroll on Android can change scale causing a lot of raster.
// This is wasteful and visually unnecessary since it's a short animation
// that resets the scale at the end. When enabled, this aovids recomputing
// raster scale during elastic overscroll.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kAvoidRasterDuringElasticOverscroll);

// When enabled, the double tap to zoom will be disabled when the viewport
// meta tag is properly set for mobile using content=width=device-width
// or content=initial-scale=1.0
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kRemoveMobileViewportDoubleTap);

// When enabled, all scrolling is performed on the compositor thread -
// delegating only the hit test to Blink. This causes Blink to send additional
// information in the scroll property tree. When a scroll can't be hit tested
// on the compositor, it will post a hit test task to Blink and continue the
// scroll when that resolves. For details, see:
// https://docs.google.com/document/d/1smLAXs-DSLLmkEt4FIPP7PVglJXOcwRc7A5G0SEwxaY/edit
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kScrollUnification);

// When enabled, wheel scrolls trigger smoothness mode. When disabled,
// smoothness mode is limited to non-animated (precision) scrolls, such as
// touch scrolling.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kSchedulerSmoothnessForAnimatedScrolls);

// When enabled, cc will show blink's Web-Vital metrics inside its heads up
// display.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kHudDisplayForPerformanceMetrics);

// When enabled, some jank is injected to the animation/scrolling pipeline.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kJankInjectionAblationFeature);

// When enabled, scheduler tree priority will change to
// NEW_CONTENT_TAKES_PRIORITY if during a scrollbar scroll, CC has to
// checkerboard.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kPreferNewContentForCheckerboardedScrolls);

// When enabled, CompositorTimingHistory will directly record the timing history
// that is used to calculate main thread timing estimates, and use the
// percentile of sum of different stages instead of the sum of percentiles.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(
    kDurationEstimatesInCompositorTimingHistory);

// When enabled, the main thread does not block while commit is running on the
// impl thread.
// WARNING: This feature is not yet safe to enable. Work is needed to ensure
// that main thread cc data structures are not modified on the main thread while
// commit is running concurrently on the impl thread.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kNonBlockingCommit);

// When enabled, DroppedFrameCounter will use an adjusted sliding window
// interval specified by field trial params.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kSlidingWindowForDroppedFrameCounter);

// When enabled, SupportsBackgroundThreadPriority is set to kNo for
// GpuImageDecodeTaskImpl and SoftwareImageDecodeTaskImpl.
// Introduced to fix https://crbug.com/1116624
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kNormalPriorityImageDecoding);

// When enabled commits are aborted if scroll and viewport state from CC could
// not be synchronized at the beginning of the frame because main frames were
// being deferred.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(
    kSkipCommitsIfNotSynchronizingCompositorState);

// Use DMSAA instead of MSAA for rastering tiles.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kUseDMSAAForTiles);

// Updating browser controls state will IPC directly from browser main to the
// compositor thread. Previously this proxied through the renderer main thread.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kUpdateBrowserControlsWithoutProxy);

// Fix the SMOOTHNESS_TAKES_PRIORITY queue priorities used in
// RasterTilePriorityQueueAll::GetNextQueues(). By fixing the bug which fails to
// schedule raster tasks for Pending SOON tiles, it reduces checkerboarding and
// improves the rendering.desktop tough_scrolling benchmark.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kRasterTilePriorityQueue);

// Enables shared image cache for gpu used by CC instances instantiated for UI.
// TODO(https://crbug.com/c/1378251): this shall also be possible to use by
// renderers.
CC_BASE_EXPORT BASE_DECLARE_FEATURE(kUIEnableSharedImageCacheForGpu);

}  // namespace features

#endif  // CC_BASE_FEATURES_H_