Schedule bitmap animation timers on the compositor task runner.

third_party/WebKit/Source/platform/WebFrameScheduler.h

Index: third_party/WebKit/Source/platform/WebFrameScheduler.h
diff --git a/third_party/WebKit/Source/platform/WebFrameScheduler.h b/third_party/WebKit/Source/platform/WebFrameScheduler.h
index f1ea4505332ce61291aa6c0abb5be50199cd01e6..2f490a8ee5ba7980535134291eb4cc1c2f511453 100644
--- a/third_party/WebKit/Source/platform/WebFrameScheduler.h
+++ b/third_party/WebKit/Source/platform/WebFrameScheduler.h
@@ -51,6 +51,10 @@ class WebFrameScheduler {
   // WebFrameScheduler owns the returned WebTaskRunner.
   virtual RefPtr<WebTaskRunner> TimerTaskRunner() = 0;
 
+  // Returns the WebTaskRunner for compositor tasks.
+  // WebFrameScheduler owns the returned WebTaskRunner.
+  virtual RefPtr<WebTaskRunner> CompositorTaskRunner() = 0;
+
   // Returns the WebTaskRunner for tasks which shouldn't get throttled,
   // but can be suspended.
   // TODO(altimin): This is a transitional task runner. Unthrottled task runner