Aura: Allow browser UI thread waiting for compositor commits.

base/threading/thread_restrictions.h

Index: base/threading/thread_restrictions.h
diff --git a/base/threading/thread_restrictions.h b/base/threading/thread_restrictions.h
index 3effc9c6a30dce20f135914533b1114b1d2d4c25..61a269f349c158d5ba7d59570930567728de4706 100644
--- a/base/threading/thread_restrictions.h
+++ b/base/threading/thread_restrictions.h
@@ -29,6 +29,9 @@ namespace browser_sync {
 class NonFrontendDataTypeController;
 class UIModelWorker;
 }
+namespace cc {
+class CCCompletionEvent;
+}
 namespace chromeos {
 class AudioMixerAlsa;
 class BlockingMethodCaller;
@@ -168,6 +171,7 @@ class BASE_EXPORT ThreadRestrictions {
   friend class ::HistogramSynchronizer;
   friend class ::ScopedAllowWaitForLegacyWebViewApi;
   friend class ::TestingAutomationProvider;
+  friend class cc::CCCompletionEvent;
   friend class remoting::AutoThread;
   friend class SequencedWorkerPool;
   friend class SimpleThread;