Replaced BackgroundAnimator with ShelfBackgroundAnimator.

ash/common/shelf/shelf_background_animator_observer.h

+// Copyright 2016 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 ASH_COMMON_SHELF_SHELF_BACKGROUND_ANIMATOR_OBSERVER_H_
+#define ASH_COMMON_SHELF_SHELF_BACKGROUND_ANIMATOR_OBSERVER_H_
+
+#include "ash/ash_export.h"
+
+namespace ash {
+
+// Observer for the ShelfBackgroundAnimator class.
+class ASH_EXPORT ShelfBackgroundAnimatorObserver {
+ public:
+  // Called when the Shelf's opaque background should be updated.
+  virtual void UpdateShelfOpaqueBackground(int alpha) {}
+
+  // Called when the Shelf's asset based background should be updated.
+  // TODO(bruthig): Remove when non-md is no longer needed (crbug.com/614453).
+  virtual void UpdateShelfAssetBackground(int alpha) {}
+
+  // Called when the Shelf item (aka button) backgrounds should be updated.
+  virtual void UpdateShelfItemBackground(int alpha) {}
+
+ protected:
+  virtual ~ShelfBackgroundAnimatorObserver() {}
+};
+
+}  // namespace ash
+
+#endif  // ASH_COMMON_SHELF_SHELF_BACKGROUND_ANIMATOR_OBSERVER_H_