Makes Panel related classes use ash/wm/common types

ash/wm/common/wm_globals.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_WM_COMMON_WM_GLOBALS_H_
 #define ASH_WM_COMMON_WM_GLOBALS_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "ash/ash_export.h"
 
 namespace gfx {
 class Rect;
 }
 
 namespace ash {
 
 class UserMetricsRecorder;
 
 namespace wm {
 
 class WmActivationObserver;
+class WmDisplayObserver;
+class WmOverviewModeObserver;
 class WmWindow;
 
 // Used for accessing global state.
 class ASH_EXPORT WmGlobals {
  public:
   virtual ~WmGlobals() {}
 
   // This is necessary for a handful of places that is difficult to plumb
   // through context.
   static WmGlobals* Get();
@@ skipping 20 matching lines @@
   // See aura::client::CursorClient for details on these.
   virtual void LockCursor() = 0;
   virtual void UnlockCursor() = 0;
 
   virtual std::vector<WmWindow*> GetAllRootWindows() = 0;
 
   virtual UserMetricsRecorder* GetUserMetricsRecorder() = 0;
 
   virtual void AddActivationObserver(WmActivationObserver* observer) = 0;
   virtual void RemoveActivationObserver(WmActivationObserver* observer) = 0;
+
+  virtual void AddDisplayObserver(WmDisplayObserver* observer) = 0;
+  virtual void RemoveDisplayObserver(WmDisplayObserver* observer) = 0;
+
+  virtual void AddOverviewModeObserver(WmOverviewModeObserver* observer) = 0;
+  virtual void RemoveOverviewModeObserver(WmOverviewModeObserver* observer) = 0;
 };
 
 }  // namespace wm
 }  // namespace ash
 
 #endif  // ASH_WM_COMMON_WM_GLOBALS_H_