Replaced BackgroundAnimator with ShelfBackgroundAnimator.

ash/shelf/shelf_background_animator.h

Index: ash/shelf/shelf_background_animator.h
diff --git a/ash/shelf/shelf_background_animator.h b/ash/shelf/shelf_background_animator.h
new file mode 100644
index 0000000000000000000000000000000000000000..1f0d48bee0e63164b31c4429c33c84b46811ffd9
--- /dev/null
+++ b/ash/shelf/shelf_background_animator.h
@@ -0,0 +1,72 @@
+// 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.
+
+#include <vector>
+
+#include "ash/ash_export.h"
+#include "ash/common/wm/background_animator.h"
+#include "ash/shelf/shelf_layout_manager_observer.h"
+#include "base/macros.h"
+
+namespace ash {
+
+class ShelfBackgroundAnimatorDelegate;
+

[James Cook, 2016/06/09 23:40:37]

This will need a good class comment.

[bruthig, 2016/06/14 16:40:44]

Acknowledged.

+class ASH_EXPORT ShelfBackgroundAnimator : public ShelfLayoutManagerObserver,

[James Cook, 2016/06/09 23:40:37]

I think it would be better if this class lived in //ash/common/shelf. I'm in the
process of migrating shelf code there.

This class could derive from WmShelfObserver, and you would need to extend
WmShelfObserver to have an OnBackgroundUpdated() method, but that shouldn't be
too hard.

[bruthig, 2016/06/14 16:40:44]

Done.

+                                           public BackgroundAnimatorDelegate {
+ public:
+  ShelfBackgroundAnimator();
+  ~ShelfBackgroundAnimator() override;
+
+  ShelfBackgroundType target_background_type() const {
+    return target_background_type_;
+  }
+
+  void AddShelfBackgroundDelegate(ShelfBackgroundAnimatorDelegate* delegate);
+
+  void AddShelfItemBackgroundDelegate(
+      ShelfBackgroundAnimatorDelegate* delegate);
+
+  void PaintBackground(ShelfBackgroundType background_type,
+                       BackgroundAnimatorChangeType change_type);
+
+ protected:
+  // ShelfLayoutManagerObserver:
+  void OnBackgroundUpdated(ShelfBackgroundType background_type,
+                           BackgroundAnimatorChangeType change_type) override;
+
+  // BackgroundAnimatorDelegate:
+  void UpdateBackground(BackgroundAnimator* animator, int alpha) override;
+  void BackgroundAnimationEnded(bool successfully) override;
+
+ private:
+  using DelegateList = std::vector<ShelfBackgroundAnimatorDelegate*>;
+
+  void UpdateDelegates(DelegateList delegates, int alpha);
+
+  void CreateAnimators(ShelfBackgroundType background_type,
+                       BackgroundAnimatorChangeType change_type);
+
+  void ConfigureAnimatorsDuration(ShelfBackgroundType background_type,
+                                  BackgroundAnimatorChangeType change_type);
+
+  ShelfBackgroundType target_background_type_;
+  ShelfBackgroundType previous_background_type_;
+
+  int previous_shelf_alpha_;
+
+  int previous_shelf_item_alpha_;
+
+  std::unique_ptr<BackgroundAnimator> shelf_background_animator_;
+
+  std::unique_ptr<BackgroundAnimator> shelf_item_background_animator_;
+
+  DelegateList shelf_background_delegates_;
+
+  DelegateList shelf_item_background_delegates_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShelfBackgroundAnimator);
+};
+
+}  // namespace ash