cc: Block commit on activate by setting a flag on LayerTreeHost.

cc/trees/thread_proxy.h

Index: cc/trees/thread_proxy.h
diff --git a/cc/trees/thread_proxy.h b/cc/trees/thread_proxy.h
index d159eb568e6d72388d58b0cf038f3624eb7e4d56..8122bf4e7d1bc873edce164b3c9d92a15a9dfcf3 100644
--- a/cc/trees/thread_proxy.h
+++ b/cc/trees/thread_proxy.h
@@ -52,6 +52,7 @@ class ThreadProxy : public Proxy,
   virtual void SetNeedsUpdateLayers() OVERRIDE;
   virtual void SetNeedsCommit() OVERRIDE;
   virtual void SetNeedsRedraw(gfx::Rect damage_rect) OVERRIDE;
+  virtual void SetNextCommitWaitsForActivation() OVERRIDE;
   virtual void NotifyInputThrottledUntilCommit() OVERRIDE;
   virtual void SetDeferCommits(bool defer_commits) OVERRIDE;
   virtual bool CommitRequested() const OVERRIDE;
@@ -204,6 +205,10 @@ class ThreadProxy : public Proxy,
   // anything else.
   scoped_ptr<OutputSurface> first_output_surface_;
 
+  // Accessed on the main thread, or when main thread is blocked.
+  bool commit_waits_for_activation_;
+  bool inside_commit_;
+
   base::WeakPtrFactory<ThreadProxy> weak_factory_on_impl_thread_;
 
   base::WeakPtr<ThreadProxy> main_thread_weak_ptr_;