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

ui/aura/window_event_dispatcher.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/aura/window_event_dispatcher.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 477 matching lines @@
 bool WindowEventDispatcher::CanDispatchToTarget(ui::EventTarget* target) {
   return event_dispatch_target_ == target;
 }
 
 ui::EventDispatchDetails WindowEventDispatcher::PreDispatchEvent(
     ui::EventTarget* target,
     ui::Event* event) {
   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) {
       if (can_be_held)
         held_move_event_.reset();
       DispatchDetails details = DispatchHeldEvents();
       if (details.dispatcher_destroyed || details.target_destroyed)
         return details;
     }
   }
@@ skipping 408 matching lines @@
   }
 
   // This flag is set depending on the gestures recognized in the call above,
   // and needs to propagate with the forwarded event.
   event->set_may_cause_scrolling(orig_event.may_cause_scrolling());
 
   return PreDispatchLocatedEvent(target, event);
 }
 
 }  // namespace aura