Record the fraction of the time without user input - Aura only

ui/aura/window_event_dispatcher.cc

Index: ui/aura/window_event_dispatcher.cc
diff --git a/ui/aura/window_event_dispatcher.cc b/ui/aura/window_event_dispatcher.cc
index 78ecee4d4604dcd3bc4fbde6f6c77c4b65b654e4..46c7957a80fd0c68bb81b890c0b47cf283f591a8 100644
--- a/ui/aura/window_event_dispatcher.cc
+++ b/ui/aura/window_event_dispatcher.cc
@@ -495,6 +495,9 @@ ui::EventDispatchDetails WindowEventDispatcher::PreDispatchEvent(
   Window* target_window = static_cast<Window*>(target);
   CHECK(window()->Contains(target_window));
 
+  fraction_of_time_without_user_input_recorder_.RecordEventAtTime(
+      event->time_stamp());

[sadrul, 2017/03/19 00:38:51]

Do you care whether the event is actually coming from user, or was generated
internally by aura (e.g. if a window moved/closed/opened etc.)? If so, you can
look at the EF_IS_SYNTHESIZED flag.

[tdresser, 2017/03/24 14:56:30]

Done.

+
   if (!dispatching_held_event_) {
     bool can_be_held = IsEventCandidateForHold(*event);
     if (!move_hold_count_ || !can_be_held) {