cc: Add main frame timing info to frame timing tracker.

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 1f0661160001cbe25b2e73ad9f2bfff4dc3bb65e..d8f47480aaa01fd5a114a05209cd5f6f5733a735 100644
--- a/cc/trees/thread_proxy.h
+++ b/cc/trees/thread_proxy.h
@@ -143,6 +143,10 @@ class CC_EXPORT ThreadProxy : public Proxy,
 
     scoped_ptr<BeginFrameSource> external_begin_frame_source;
 
+    // Values used to keep track of frame durations. Used only in frame timing.
+    BeginFrameArgs last_begin_main_frame_args;
+    BeginFrameArgs last_processed_begin_main_frame_args;
+
     scoped_ptr<LayerTreeHostImpl> layer_tree_host_impl;
     base::WeakPtrFactory<ThreadProxy> weak_factory;
   };