cc: Track BeginMainFrame more precisely in CompositorTimingHistory.

cc/trees/channel_main.h

Index: cc/trees/channel_main.h
diff --git a/cc/trees/channel_main.h b/cc/trees/channel_main.h
index a9f51739c9571befc9b95bfbf4dd51edddd6f362..d632c1ffa6df73aa02e6f2b4057da8e7cf1090f7 100644
--- a/cc/trees/channel_main.h
+++ b/cc/trees/channel_main.h
@@ -43,8 +43,11 @@ class CC_EXPORT ChannelMain {
       bool* main_frame_will_happen) = 0;
   virtual void SetNeedsRedrawOnImpl(const gfx::Rect& damage_rect) = 0;
   virtual void SetNeedsCommitOnImpl() = 0;
-  virtual void BeginMainFrameAbortedOnImpl(CommitEarlyOutReason reason) = 0;
-  virtual void StartCommitOnImpl(CompletionEvent* completion) = 0;
+  virtual void BeginMainFrameAbortedOnImpl(
+      CommitEarlyOutReason reason,
+      base::TimeTicks main_thread_start_time) = 0;
+  virtual void StartCommitOnImpl(CompletionEvent* completion,
+                                 base::TimeTicks main_thread_start_time) = 0;
 
   virtual ~ChannelMain() {}
 };