UMA metrics for fractions of wheel and touch scrolls blocked on the main thread.

ui/events/blink/input_handler_proxy.h

Index: ui/events/blink/input_handler_proxy.h
diff --git a/ui/events/blink/input_handler_proxy.h b/ui/events/blink/input_handler_proxy.h
index 6f86d22ad5378782323b8d32429af0fddef7c3ea..c95078a694b26efae5954fa00903977bd44c3017 100644
--- a/ui/events/blink/input_handler_proxy.h
+++ b/ui/events/blink/input_handler_proxy.h
@@ -117,6 +117,8 @@ class InputHandlerProxy
  protected:
   void RecordMainThreadScrollingReasons(blink::WebGestureDevice device,
                                         uint32_t reasons);
+  void RecordScrollingThreadStatus(blink::WebGestureDevice device,
+                                   uint32_t reasons);
 
  private:
   friend class test::InputHandlerProxyTest;
@@ -244,6 +246,8 @@ class InputHandlerProxy
   // passive events not to block scrolling.
   int32_t touch_start_result_;
 
+  int32_t mouse_wheel_result_;

[tdresser, 2017/01/17 20:27:43]

Comment.

[sahel, 2017/01/19 15:26:32]

Done.

+
   base::TimeTicks last_fling_animate_time_;
 
   // Used to record overscroll notifications while an event is being