Allow ui::Compositor to disable commits during tab-switch

cc/trees/proxy.h

Index: cc/trees/proxy.h
diff --git a/cc/trees/proxy.h b/cc/trees/proxy.h
index 539effeda7a9588414adeea6061c67e3c79e199d..5c725eede9030515306fb0a7ea3ec81ae040e313 100644
--- a/cc/trees/proxy.h
+++ b/cc/trees/proxy.h
@@ -80,9 +80,9 @@ class CC_EXPORT Proxy {
 
   virtual void NotifyInputThrottledUntilCommit() = 0;
 
-  // Defers commits until it is reset. It is only supported when in threaded
-  // mode. It's an error to make a sync call like CompositeAndReadback while
-  // commits are deferred.
+  // Defers commits until it is reset. It is only supported when using a
+  // scheduler. It's an error to make a sync call like CompositeAndReadback

[danakj, 2015/03/11 17:22:55]

Ahaha CompositeAndReadback is no more, missed this comment. Can you just remove
the whole "It's an error" bit?

[ccameron, 2015/03/11 21:46:43]

Done.

+  // while commits are deferred.
   virtual void SetDeferCommits(bool defer_commits) = 0;
 
   virtual void MainThreadHasStoppedFlinging() = 0;