mash: Minor ash/common fixes for tray_display.

ash/system/chromeos/tray_display.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_SYSTEM_CHROMEOS_TRAY_DISPLAY_H_
 #define ASH_SYSTEM_CHROMEOS_TRAY_DISPLAY_H_
 
 #include <stdint.h>
 
 #include <map>
 
 #include "ash/ash_export.h"
 #include "ash/common/display/display_info.h"
 #include "ash/common/system/tray/system_tray_item.h"
-#include "ash/display/window_tree_host_manager.h"
+#include "ash/common/wm_display_observer.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "ui/views/view.h"
 
 namespace ash {
+
 class DisplayView;
 
-namespace test {
-class AshTestBase;
-}
-
-class ASH_EXPORT TrayDisplay : public SystemTrayItem,
-                               public WindowTreeHostManager::Observer {
+class ASH_EXPORT TrayDisplay : public SystemTrayItem, public WmDisplayObserver {
  public:
   explicit TrayDisplay(SystemTray* system_tray);
   ~TrayDisplay() override;
 
-  // Overridden from WindowTreeHostManagerObserver:
+  // Overridden from WmDisplayObserver:
   void OnDisplayConfigurationChanged() override;
 
  private:
   friend class TrayDisplayTest;
 
   typedef std::map<int64_t, DisplayInfo> DisplayInfoMap;
 
   static const char kNotificationId[];
 
   // Scans the current display info and updates |display_info_|. Sets the
@@ skipping 27 matching lines @@
 
   DisplayView* default_;
   DisplayInfoMap display_info_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayDisplay);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_CHROMEOS_TRAY_DISPLAY_H_