Remove DisplayChangeObserver ash dependencies.

ash/display/window_tree_host_manager.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_DISPLAY_DISPLAY_CONTROLLER_H_
-#define ASH_DISPLAY_DISPLAY_CONTROLLER_H_
+#ifndef ASH_DISPLAY_WINDOW_TREE_HOST_MANAGER_H_
+#define ASH_DISPLAY_WINDOW_TREE_HOST_MANAGER_H_
 
 #include <stdint.h>
 
 #include <map>
 #include <memory>
 #include <vector>
 
 #include "ash/ash_export.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
@@ skipping 136 matching lines @@
 
   // display::DisplayManager::Delegate overrides:
   void CreateOrUpdateMirroringDisplay(
       const display::DisplayInfoList& info_list) override;
   void CloseMirroringDisplayIfNotNecessary() override;
   void PreDisplayConfigurationChange(bool clear_focus) override;
   void PostDisplayConfigurationChange(bool must_clear_window) override;
 #if defined(OS_CHROMEOS)
   ui::DisplayConfigurator* display_configurator() override;
 #endif
-  std::string GetInternalDisplayNameString() override;
-  std::string GetUnknownDisplayNameString() override;
 
   // ui::internal::InputMethodDelegate overrides:
   ui::EventDispatchDetails DispatchKeyEventPostIME(
       ui::KeyEvent* event) override;
 
   InputMethodEventHandler* input_method_event_handler() {
     return input_method_event_handler_.get();
   }
 
  private:
@@ skipping 41 matching lines @@
   // should be moved after a display configuration change.
   int64_t cursor_display_id_for_restore_;
 
   base::WeakPtrFactory<WindowTreeHostManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeHostManager);
 };
 
 }  // namespace ash
 
-#endif  // ASH_DISPLAY_DISPLAY_CONTROLLER_H_
+#endif  // ASH_DISPLAY_WINDOW_TREE_HOST_MANAGER_H_