Plumb activation time to main

cc/scheduler/scheduler.h

Index: cc/scheduler/scheduler.h
diff --git a/cc/scheduler/scheduler.h b/cc/scheduler/scheduler.h
index b22e9c3757254ca235da8449177602cece5e71cf..79b86204daeccd874b11b81f923254b807d89cf2 100644
--- a/cc/scheduler/scheduler.h
+++ b/cc/scheduler/scheduler.h
@@ -77,7 +77,7 @@ class CC_EXPORT Scheduler : public BeginFrameObserverBase {
   void SetVisible(bool visible);
   bool visible() { return state_machine_.visible(); }
   void SetCanDraw(bool can_draw);
-  void NotifyReadyToActivate();
+  void NotifyReadyToActivate(int source_frame_number);
   void NotifyReadyToDraw();
   void SetBeginFrameSource(BeginFrameSource* source);
 
@@ -191,6 +191,13 @@ class CC_EXPORT Scheduler : public BeginFrameObserverBase {
 
   bool stopped_ = false;
 
+  // This is to report Activation (ReadyToActivate signal) time back to Main.
+  // A vector of pairs of source_frame_number and timestamp is captured, and
+  // sent back in BeginFrameArgs with the next ProxyMain::BeginMainFrame. A
+  // vector is needed as there can be multiple ReadyToActivate signals before
+  // the next BeginMainFrame.
+  std::vector<std::pair<uint32_t, base::TimeTicks>> ready_to_activate_time_;
+
  private:
   void ScheduleBeginImplFrameDeadline();
   void ScheduleBeginImplFrameDeadlineIfNeeded();