Replace WmWindowObserver with aura::WindowObserver.

ash/common/wm/workspace/multi_window_resize_controller.h

 // Copyright (c) 2012 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_WM_WORKSPACE_MULTI_WINDOW_RESIZE_CONTROLLER_H_
 #define ASH_COMMON_WM_WORKSPACE_MULTI_WINDOW_RESIZE_CONTROLLER_H_
 
 #include <memory>
 #include <vector>
 
 #include "ash/ash_export.h"
-#include "ash/common/wm_window_observer.h"
 #include "base/macros.h"
 #include "base/timer/timer.h"
+#include "ui/aura/window_observer.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/views/mouse_watcher.h"
 
 namespace views {
 class Widget;
 }
 
 namespace ash {
 class MultiWindowResizeControllerTest;
+class WmWindow;
 class WorkspaceWindowResizer;
 
 // Two directions resizes happen in.
 enum Direction {
   TOP_BOTTOM,
   LEFT_RIGHT,
 };
 
 // MultiWindowResizeController is responsible for determining and showing a
 // widget that allows resizing multiple windows at the same time.
 // MultiWindowResizeController is driven by WorkspaceEventFilter.
 class ASH_EXPORT MultiWindowResizeController
     : public views::MouseWatcherListener,
-      public WmWindowObserver {
+      public aura::WindowObserver {
  public:
   MultiWindowResizeController();
   ~MultiWindowResizeController() override;
 
   // If necessary, shows the resize widget. |window| is the window the mouse
   // is over, |component| the edge and |point| the location of the mouse.
   void Show(WmWindow* window, int component, const gfx::Point& point);
 
   // Hides the resize widget.
   void Hide();
 
   // MouseWatcherListenre overrides:
   void MouseMovedOutOfHost() override;
 
   // WindowObserver overrides:
-  void OnWindowDestroying(WmWindow* window) override;
+  void OnWindowDestroying(aura::Window* window) override;
 
  private:
   friend class MultiWindowResizeControllerTest;
 
   // Used to track the two resizable windows and direction.
   struct ResizeWindows {
     ResizeWindows();
     ResizeWindows(const ResizeWindows& other);
     ~ResizeWindows();
 
@@ skipping 106 matching lines @@
   // |resize_widget_| is non-NULL (ie the widget is showing) we ignore calls
   // to Show().
   std::unique_ptr<views::MouseWatcher> mouse_watcher_;
 
   DISALLOW_COPY_AND_ASSIGN(MultiWindowResizeController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_WORKSPACE_MULTI_WINDOW_RESIZE_CONTROLLER_H_