Added UMA stats to overview mode

ash/wm/window_cycle_controller.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 "ash/wm/window_cycle_controller.h"
 
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/window_cycle_list.h"
+#include "base/metrics/histogram.h"
 #include "ui/events/event.h"
 #include "ui/events/event_handler.h"
 
 namespace ash {
 
 namespace {
 
 // Filter to watch for the termination of a keyboard gesture to cycle through
 // multiple windows.
 class WindowCycleEventFilter : public ui::EventHandler {
@@ skipping 51 matching lines @@
   if (!IsCycling())
     StartCycling();
 
   Step(direction);
 }
 
 void WindowCycleController::StartCycling() {
   window_cycle_list_.reset(new WindowCycleList(ash::Shell::GetInstance()->
       mru_window_tracker()->BuildMruWindowList()));
   event_handler_.reset(new WindowCycleEventFilter());
+  cycle_start_time_ = base::Time::Now();
+  Shell::GetInstance()->metrics()->RecordUserMetricsAction(UMA_WINDOW_CYCLE);
 }
 
 //////////////////////////////////////////////////////////////////////////////
 // WindowCycleController, private:
 
 void WindowCycleController::Step(Direction direction) {
   DCHECK(window_cycle_list_.get());
   window_cycle_list_->Step(direction);
 }
 
 void WindowCycleController::StopCycling() {
   window_cycle_list_.reset();
   // Remove our key event filter.
   event_handler_.reset();
+  UMA_HISTOGRAM_MEDIUM_TIMES("Ash.WindowCycleController.CycleTime",
+                             base::Time::Now() - cycle_start_time_);
 }
 
 }  // namespace ash