Run smooth scroll animations on the compositor when possible

third_party/WebKit/Source/platform/scroll/ScrollAnimator.h

Index: third_party/WebKit/Source/platform/scroll/ScrollAnimator.h
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollAnimator.h b/third_party/WebKit/Source/platform/scroll/ScrollAnimator.h
index 01746e683e176296ad1cc6b591801b1803e85b90..b1be4a28d8d8fe5f3d537fc20cc3b888d375bd16 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollAnimator.h
+++ b/third_party/WebKit/Source/platform/scroll/ScrollAnimator.h
@@ -34,13 +34,16 @@
 #include "platform/Timer.h"
 #include "platform/geometry/FloatPoint.h"
 #include "platform/scroll/ScrollAnimatorBase.h"
+#include "public/platform/WebCompositorAnimationDelegate.h"
+#include "public/platform/WebCompositorAnimationPlayerClient.h"
 #include "public/platform/WebScrollOffsetAnimationCurve.h"
 
 namespace blink {
 
 class ScrollAnimatorTest;
+class WebCompositorAnimationTimeline;
 
-class PLATFORM_EXPORT ScrollAnimator final : public ScrollAnimatorBase {
+class PLATFORM_EXPORT ScrollAnimator final : public ScrollAnimatorBase  {

[skobes, 2015/12/18 19:05:58]

extra space before {

[ymalik, 2015/12/18 19:35:47]

Done.

 public:
     explicit ScrollAnimator(ScrollableArea*, WTF::TimeFunction = WTF::monotonicallyIncreasingTime);
     ~ScrollAnimator() override;
@@ -50,20 +53,27 @@ public:
     ScrollResultOneDimensional userScroll(ScrollbarOrientation, ScrollGranularity, float step, float delta) override;
     void scrollToOffsetWithoutAnimation(const FloatPoint&) override;
 
-    void cancelAnimations() override;
-    void serviceScrollAnimations() override;
-    bool hasRunningAnimation() const override;
+    // ScrollAnimatorCompositorCoordinator implementation.
+    void tickAnimation(double monotonicTime) override;
+    void cancelAnimation() override;
+    void resetAnimationState() override;
+    void updateCompositorAnimations() override;
+    void notifyCompositorAnimationFinished(int groupId) override;
+    void layerForCompositedScrollingDidChange(WebCompositorAnimationTimeline*) override;
 
     DECLARE_VIRTUAL_TRACE();
 
 protected:
-    void animationTimerFired();
-
     OwnPtr<WebScrollOffsetAnimationCurve> m_animationCurve;
+    double m_lastTickTime;
     double m_startTime;
     WTF::TimeFunction m_timeFunction;
+
 private:
     FloatPoint desiredTargetPosition() const;
+
+    FloatPoint m_targetOffset;

[skobes, 2015/12/18 19:05:57]

Why is this needed here if it's also stored in m_animationCurve?

[ymalik, 2015/12/18 19:35:47]

m_animationCurve is actually set when updateCompositorAnimations is called.
m_targetOffset is the variable that stores the new target offset from when
ScrollAnimator::userScroll is called.

+    FloatPoint m_initialOffset;

[skobes, 2015/12/18 19:05:58]

This seems unused?

[ymalik, 2015/12/18 19:35:47]

Oops. Forgot to remove after testing. Thanks.

 };
 
 } // namespace blink