Add OnDisplayMetricsChanged in DisplayObserver.

ash/system/web_notification/web_notification_tray.cc

 // 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.
 
 #include "ash/system/web_notification/web_notification_tray.h"
 
 #include "ash/ash_switches.h"
 #include "ash/root_window_controller.h"
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shelf/shelf_layout_manager_observer.h"
@@ skipping 140 matching lines @@
   Shell::GetInstance()->RemoveShellObserver(this);
   if (shelf_)
     shelf_->RemoveObserver(this);
   collection_ = NULL;
   shelf_ = NULL;
 }
 
 void WorkAreaObserver::OnDisplayWorkAreaInsetsChanged() {
   UpdateShelf();
 
-  collection_->OnDisplayBoundsChanged(
+  collection_->OnDisplayMetricsChanged(
       Shell::GetScreen()->GetDisplayNearestWindow(
-          shelf_->shelf_widget()->GetNativeView()));
+          shelf_->shelf_widget()->GetNativeView()),
+      gfx::DisplayObserver::DISPLAY_METRIC_WORK_AREA);
 }
 
 void WorkAreaObserver::OnAutoHideStateChanged(ShelfAutoHideState new_state) {
   gfx::Display display = Shell::GetScreen()->GetDisplayNearestWindow(
       shelf_->shelf_widget()->GetNativeView());
   gfx::Rect work_area = display.work_area();
   int width = 0;
   if ((shelf_->visibility_state() == SHELF_AUTO_HIDE) &&
       new_state == SHELF_AUTO_HIDE_SHOWN) {
     // Since the work_area is already reduced by kAutoHideSize, the inset width
@@ skipping 438 matching lines @@
 
 message_center::MessageCenterBubble*
 WebNotificationTray::GetMessageCenterBubbleForTest() {
   if (!message_center_bubble())
     return NULL;
   return static_cast<message_center::MessageCenterBubble*>(
       message_center_bubble()->bubble());
 }
 
 }  // namespace ash