Add fade to white animation when power button is pressed on Athena

athena/system/power_button_controller.h

 // 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.
 
 #ifndef ATHENA_SYSTEM_POWER_BUTTON_CONTROLLER_H_
 #define ATHENA_SYSTEM_POWER_BUTTON_CONTROLLER_H_
 
+#include "base/time/time.h"
 #include "chromeos/dbus/power_manager_client.h"
+#include "ui/compositor/layer_animation_observer.h"
 
 namespace athena {
 
 // Shuts down in response to the power button being pressed.
-class PowerButtonController : public chromeos::PowerManagerClient::Observer {
+class PowerButtonController : public chromeos::PowerManagerClient::Observer,
+                              public ui::ImplicitAnimationObserver {
  public:
   PowerButtonController();
   virtual ~PowerButtonController();
 
+ private:
+  // Starts an animation of the root window to |target| brightness and
+  // grayscale.
+  void StartGrayscaleAndBrightnessAnimation(float target,
+                                            int duration_ms,
+                                            gfx::Tween::Type tween_type);
+
+  // Requests system shutdown on the D-Bus.
+  void Shutdown();
+
   // chromeos::PowerManagerClient::Observer:
   virtual void BrightnessChanged(int level, bool user_initiated) OVERRIDE;
   virtual void PowerButtonEventReceived(
       bool down,
       const base::TimeTicks& timestamp) OVERRIDE;
 
- private:
+  // ui::ImplicitAnimationObserver:
+  virtual void OnImplicitAnimationsCompleted() OVERRIDE;
+
   // Whether the screen brightness was reduced to 0%.
   bool brightness_is_zero_;
 
   // The last time at which the screen brightness was 0%.
   base::TimeTicks zero_brightness_end_time_;
 
   // Whether shutdown was requested.
   bool shutdown_requested_;
 
+  // Whether the shutdown request can be canceled.
+  bool can_cancel_shutdown_;
+
   DISALLOW_COPY_AND_ASSIGN(PowerButtonController);
 };
 
 }  // namespace athena
 
 #endif  // ATHENA_SYSTEM_POWER_BUTTON_CONTROLLER_H_