Communicate MT changes to impl-only scroll offset animations

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

Index: third_party/WebKit/Source/platform/scroll/ScrollAnimatorCompositorCoordinator.h
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollAnimatorCompositorCoordinator.h b/third_party/WebKit/Source/platform/scroll/ScrollAnimatorCompositorCoordinator.h
index 9b69df747f69c2eef0b5c786e4b457f06511894c..752728e2b3f8310309d9a0f1de8b2230b1a798b6 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollAnimatorCompositorCoordinator.h
+++ b/third_party/WebKit/Source/platform/scroll/ScrollAnimatorCompositorCoordinator.h
@@ -7,6 +7,7 @@
 
 #include "base/gtest_prod_util.h"
 #include "cc/animation/animation_curve.h"
+#include "cc/animation/scroll_offset_animations.h"
 #include "platform/PlatformExport.h"
 #include "platform/animation/CompositorAnimationDelegate.h"
 #include "platform/animation/CompositorAnimationPlayerClient.h"
@@ -33,6 +34,8 @@ public:
     void dispose();
     String runStateAsText() const;
 
+    void updateImplOnlyAnimationWithAdjustment(const FloatSize& adjustment);
+
     virtual bool hasRunningAnimation() const { return false; }
 
     virtual void resetAnimationState();
@@ -41,10 +44,10 @@ public:
     // and continues it on the main thread. This should only be called when in
     // DocumentLifecycle::LifecycleState::CompositingClean state.
     virtual void takeoverCompositorAnimation();
+    virtual void updateCompositorAnimations();
 
     virtual ScrollableArea* getScrollableArea() const = 0;
     virtual void tickAnimation(double monotonicTime) = 0;
-    virtual void updateCompositorAnimations() = 0;
     virtual void notifyCompositorAnimationFinished(int groupId) = 0;
     virtual void notifyCompositorAnimationAborted(int groupId) = 0;
     virtual void layerForCompositedScrollingDidChange(CompositorAnimationTimeline*) = 0;
@@ -82,6 +85,7 @@ protected:
     FRIEND_TEST_ALL_PREFIXES(ScrollAnimatorTest, AnimatedScrollTakeover);
     FRIEND_TEST_ALL_PREFIXES(ScrollAnimatorTest, CancellingAnimationResetsState);
     FRIEND_TEST_ALL_PREFIXES(ScrollAnimatorTest, CancellingCompositorAnimation);
+    FRIEND_TEST_ALL_PREFIXES(ScrollAnimatorTest, ImplOnlyAnimationUpdatesCleared);
 
     enum class RunState {
         // No animation.
@@ -127,6 +131,13 @@ protected:
     RunState m_runState;
     int m_compositorAnimationId;
     int m_compositorAnimationGroupId;
+
+    // A list of updates that happened on the main thread that may change
+    // impl-only scroll offset animations.
+    // TODO(ymalik): Currently all the updates go through ScrollAnimator
+    // ::CompositorAnimationTimeline::CompositorAnimationHost::AnimationHost.
+    // They should probably be reworked via LayerTreeView.

[loyso (OOO), 2016/05/06 01:04:38]

Since you send the updates from ScrollingCoordinator, it should be easy to write
it correctly from the beginning.
You have a pointer to WLTV to memorize in
layerTreeViewInitialized(WebLayerTreeView&
layerTreeView)/willCloseLayerTreeView.

[ymalik, 2016/05/06 05:41:49]

It's not clear to me what that would look like. The updates are sent from
ScrollAnimator not ScrollingCoordinator? Where would we store the list of
updates? Note that we can only actually add the update when the
DocumentLifecycleState is CompositingClean. 

Unless there is a good short-term reason to not do this, is this reasonable for
now?

+    std::vector<cc::ScrollOffsetAnimationUpdate> m_implOnlyAnimationUpdates;
 };
 
 } // namespace blink