Add OnDisplayMetricsChanged in DisplayObserver.

ash/shelf/shelf_window_watcher.cc

 // Copyright 2013 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.
 
 #include "ash/shelf/shelf_window_watcher.h"
 
 #include "ash/ash_switches.h"
 #include "ash/display/display_controller.h"
 #include "ash/shelf/shelf_constants.h"
 #include "ash/shelf/shelf_item_delegate_manager.h"
@@ skipping 249 matching lines @@
         GetShelfItemDetailsForWindow(window);
     SetShelfItemDetailsForShelfItem(&item, *details);
     model_->Set(index, item);
     return;
   }
 
   // Creates a new ShelfItem for |window|.
   AddShelfItem(window);
 }
 
-void ShelfWindowWatcher::OnDisplayBoundsChanged(const gfx::Display& display) {
-}
-
 void ShelfWindowWatcher::OnDisplayAdded(const gfx::Display& new_display) {
   // Add a new RootWindow and its ActivationClient to observed list.
   aura::Window* root_window = Shell::GetInstance()->display_controller()->
       GetRootWindowForDisplayId(new_display.id());
 
   // When the primary root window's display get removed, the existing root
   // window is taken over by the new display and the observer is already set.
   if (!observed_root_windows_.IsObserving(root_window))
     OnRootWindowAdded(root_window);
 }
 
 void ShelfWindowWatcher::OnDisplayRemoved(const gfx::Display& old_display) {
   // When this is called, RootWindow of |old_display| is already removed.
   // Instead, we remove an observer from RootWindow and ActivationClient in the
   // OnRootWindowDestroyed().
   // Do nothing here.
 }
 
+void ShelfWindowWatcher::OnDisplayMetricsChanged(const gfx::Display&,
+                                                 uint32_t) {
+}
+
 }  // namespace ash