compositor: Add rAF-like functionality for the UI.

ui/compositor/compositor.h

Index: ui/compositor/compositor.h
diff --git a/ui/compositor/compositor.h b/ui/compositor/compositor.h
index a10b62fcedfafd99b2c31256eafb6dfab46586ee..93a8a6043f42b2e63ce1af6421b67db4021ec451 100644
--- a/ui/compositor/compositor.h
+++ b/ui/compositor/compositor.h
@@ -16,6 +16,7 @@
 #include "cc/trees/layer_tree_host_client.h"
 #include "cc/trees/layer_tree_host_single_thread_client.h"
 #include "third_party/skia/include/core/SkColor.h"
+#include "ui/compositor/animation_frame_task.h"
 #include "ui/compositor/compositor_export.h"
 #include "ui/compositor/compositor_observer.h"
 #include "ui/compositor/layer_animator_collection.h"
@@ -129,7 +130,7 @@ class COMPOSITOR_EXPORT CompositorLock
 class COMPOSITOR_EXPORT Compositor
     : NON_EXPORTED_BASE(public cc::LayerTreeHostClient),
       NON_EXPORTED_BASE(public cc::LayerTreeHostSingleThreadClient),
-      NON_EXPORTED_BASE(public LayerAnimatorCollectionDelegate) {
+      NON_EXPORTED_BASE(public AnimationFrameTaskProvider) {
  public:
   Compositor(gfx::AcceleratedWidget widget,
              ui::ContextFactory* context_factory,
@@ -235,8 +236,9 @@ class COMPOSITOR_EXPORT Compositor
   virtual void DidPostSwapBuffers() OVERRIDE;
   virtual void DidAbortSwapBuffers() OVERRIDE;
 
-  // LayerAnimatorCollectionDelegate implementation.
-  virtual void ScheduleAnimationForLayerCollection() OVERRIDE;
+  // AnimationFrameTaskProvider:
+  virtual scoped_ptr<ScopedAnimationFrameTask> RequestAnimationFrameTask(
+      AnimationFrameTask* task) OVERRIDE;
 
   int last_started_frame() { return last_started_frame_; }
   int last_ended_frame() { return last_ended_frame_; }
@@ -254,6 +256,10 @@ class COMPOSITOR_EXPORT Compositor
   friend class base::RefCounted<Compositor>;
   friend class CompositorLock;
 
+  void RemoveAnimationFrameTask(AnimationFrameTask* task);
+
+  std::set<AnimationFrameTask*> rafs_;
+
   // Called by CompositorLock.
   void UnlockCompositor();
 
@@ -303,7 +309,7 @@ class COMPOSITOR_EXPORT Compositor
 
   LayerAnimatorCollection layer_animator_collection_;
 
-  base::WeakPtrFactory<Compositor> schedule_draw_factory_;
+  base::WeakPtrFactory<Compositor> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Compositor);
 };