Schedule bitmap animation timers on the compositor task runner.

third_party/WebKit/Source/platform/scheduler/child/web_scheduler.h

Index: third_party/WebKit/Source/platform/scheduler/child/web_scheduler.h
diff --git a/third_party/WebKit/Source/platform/scheduler/child/web_scheduler.h b/third_party/WebKit/Source/platform/scheduler/child/web_scheduler.h
index 8257671cd61b951964ed8dd95ffb99a6cd353d33..b928f19f041cd46ee40c3c515ad282a479cf7975 100644
--- a/third_party/WebKit/Source/platform/scheduler/child/web_scheduler.h
+++ b/third_party/WebKit/Source/platform/scheduler/child/web_scheduler.h
@@ -72,6 +72,11 @@ class PLATFORM_EXPORT WebScheduler {
   // Returns a WebTaskRunner for timer tasks. Can be called from any thread.
   virtual WebTaskRunner* TimerTaskRunner() = 0;
 
+  // Returns a WebTaskRunner for compositor tasks. This is intended only to be
+  // used by specific animation and rendering related tasks (e.g. animated GIFS)
+  // and should not generally be used.
+  virtual WebTaskRunner* CompositorTaskRunner() = 0;
+
   // Creates a new WebViewScheduler for a given WebView. Must be called from
   // the associated WebThread.
   virtual std::unique_ptr<WebViewScheduler> CreateWebViewScheduler(