Web Animations: Compositor start notification should only apply to animations in a matching group

Source/core/animation/CompositorPendingAnimations.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 31 matching lines @@
 // compositing update.
 // For CSS Animations, used to synchronize the start of main-thread animations
 // with compositor animations when both classes of CSS Animations are triggered
 // by the same recalc
 class CompositorPendingAnimations final {
     DISALLOW_ALLOCATION();
 public:
 
     CompositorPendingAnimations()
         : m_timer(this, &CompositorPendingAnimations::timerFired)
+        , m_compositorGroup(1)
     { }
 
     void add(AnimationPlayer*);
     // Returns whether we are waiting for an animation to start and should
     // service again on the next frame.
     bool update(bool startOnCompositor = true);
-    void notifyAnimationStarted(double monotonicAnimationStartTime, bool startedOnCompositor);
-    void notifyCompositorAnimationStarted(double monotonicAnimationStartTime);
+    void notifyCompositorAnimationStarted(double monotonicAnimationStartTime, int compositorGroup = 0);
 
     void trace(Visitor*);
 
 private:
     void timerFired(Timer<CompositorPendingAnimations>*) { update(false); }
 
     WillBeHeapVector<RefPtrWillBeMember<AnimationPlayer> > m_pending;
     WillBeHeapVector<RefPtrWillBeMember<AnimationPlayer> > m_waitingForCompositorAnimationStart;
     Timer<CompositorPendingAnimations> m_timer;
+    int m_compositorGroup;
 };
 
 } // namespace blink
 
 #endif