Refactors DockedWindowLayoutManager in terms of ash/wm/common

ash/wm/aura/wm_shelf_aura.h

Index: ash/wm/aura/wm_shelf_aura.h
diff --git a/ash/wm/aura/wm_shelf_aura.h b/ash/wm/aura/wm_shelf_aura.h
new file mode 100644
index 0000000000000000000000000000000000000000..d73d190fce9fbf8c6c634c773aaf4bc42ec39fe4
--- /dev/null
+++ b/ash/wm/aura/wm_shelf_aura.h
@@ -0,0 +1,54 @@
+// 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_WM_AURA_WM_SHELF_AURA_H_
+#define ASH_WM_AURA_WM_SHELF_AURA_H_
+
+#include "ash/ash_export.h"
+#include "ash/shelf/shelf_layout_manager_observer.h"
+#include "ash/wm/common/shelf/wm_shelf.h"
+#include "base/macros.h"
+#include "base/observer_list.h"
+
+namespace ash {
+
+class Shelf;
+class ShelfLayoutManager;
+
+namespace wm {
+
+// Aura implementation of WmShelf.
+class ASH_EXPORT WmShelfAura : public WmShelf,
+                               public ShelfLayoutManagerObserver {
+ public:
+  explicit WmShelfAura(Shelf* shelf);
+  ~WmShelfAura() override;
+
+ private:
+  // WmShelf:
+  WmWindow* GetWindow() override;
+  ShelfAlignment GetAlignment() override;
+  ShelfBackgroundType GetBackgroundType() override;
+  void UpdateVisibilityState() override;
+  void AddObserver(WmShelfObserver* observer) override;
+  void RemoveObserver(WmShelfObserver* observer) override;
+
+  // ShelfLayoutManagerObserver:
+  void WillDeleteShelf() override;
+  void OnBackgroundUpdated(wm::ShelfBackgroundType background_type,
+                           BackgroundAnimatorChangeType change_type) override;
+
+  Shelf* shelf_;
+  base::ObserverList<WmShelfObserver> observers_;
+  // ShelfLayoutManager is cached separately as it may be destroyed before
+  // WmShelfAura.
+  ShelfLayoutManager* shelf_layout_manager_;
+
+  DISALLOW_COPY_AND_ASSIGN(WmShelfAura);
+};
+
+}  // namespace wm
+}  // namespace ash
+
+#endif  // ASH_WM_AURA_WM_SHELF_AURA_H_