cc: Track BeginMainFrame more precisely in CompositorTimingHistory.

cc/trees/proxy_impl.h

Index: cc/trees/proxy_impl.h
diff --git a/cc/trees/proxy_impl.h b/cc/trees/proxy_impl.h
index 8acbb97377e108ce58d5849b55c47ca131d35709..3e6aae23a8dc1df90007cfd25e7bc8dd78e3f22b 100644
--- a/cc/trees/proxy_impl.h
+++ b/cc/trees/proxy_impl.h
@@ -35,7 +35,9 @@ class CC_EXPORT ProxyImpl {
   virtual void SetDeferCommitsOnImpl(bool defer_commits) const = 0;
   virtual void SetNeedsRedrawOnImpl(const gfx::Rect& damage_rect) = 0;
   virtual void SetNeedsCommitOnImpl() = 0;
-  virtual void BeginMainFrameAbortedOnImpl(CommitEarlyOutReason reason) = 0;
+  virtual void BeginMainFrameAbortedOnImpl(
+      CommitEarlyOutReason reason,
+      base::TimeTicks main_thread_start_time) = 0;
   virtual void FinishAllRenderingOnImpl(CompletionEvent* completion) = 0;
   virtual void SetVisibleOnImpl(CompletionEvent* completion, bool visible) = 0;
   virtual void ReleaseOutputSurfaceOnImpl(CompletionEvent* completion) = 0;
@@ -43,7 +45,8 @@ class CC_EXPORT ProxyImpl {
   virtual void MainFrameWillHappenOnImplForTesting(
       CompletionEvent* completion,
       bool* main_frame_will_happen) = 0;
-  virtual void StartCommitOnImpl(CompletionEvent* completion) = 0;
+  virtual void StartCommitOnImpl(CompletionEvent* completion,
+                                 base::TimeTicks main_thread_start_time) = 0;
 
   // TODO(khushalsagar): Rename as GetWeakPtr() once ThreadProxy is split.
   virtual base::WeakPtr<ProxyImpl> GetImplWeakPtr() = 0;