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

athena/screen/public/screen_animator.h

Index: athena/screen/public/screen_animator.h
diff --git a/athena/screen/public/screen_animator.h b/athena/screen/public/screen_animator.h
new file mode 100644
index 0000000000000000000000000000000000000000..3e9f4297ab34857446ec8ec915f5dd14d6550bd1
--- /dev/null
+++ b/athena/screen/public/screen_animator.h
@@ -0,0 +1,34 @@
+// 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_SCREEN_PUBLIC_SCREEN_ANIMATOR_H_
+#define ATHENA_SCREEN_PUBLIC_SCREEN_ANIMATOR_H_
+
+#include "athena/athena_export.h"
+
+namespace ui {
+class ImplicitAnimationObserver;
+}
+
+namespace athena {
+
+// Runs animations which affect the entire screen.
+class ATHENA_EXPORT ScreenAnimator {
+ public:
+  virtual ~ScreenAnimator() {}
+
+  enum AnimationType {
+    ANIMATION_SHUTDOWN,
+    ANIMATION_CANCEL_SHUTDOWN
+  };
+
+  // Starts an animation of |type|. If |observer| is non-NULL, it is notified
+  // when the animation completes.
+  virtual void StartAnimation(AnimationType type,
+                              ui::ImplicitAnimationObserver* observer) = 0;
+};
+
+}  // namespace athena
+
+#endif  // ATHENA_SCREEN_PUBLIC_SCREEN_ANIMATOR_H_