Invalidate all wallpaper cache if display configuration changed

ash/desktop_background/desktop_background_controller.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/desktop_background/desktop_background_controller.h"
 
 #include "ash/ash_switches.h"
 #include "ash/desktop_background/desktop_background_controller_observer.h"
 #include "ash/desktop_background/desktop_background_view.h"
 #include "ash/desktop_background/desktop_background_widget_controller.h"
@@ skipping 420 matching lines @@
 int DesktopBackgroundController::GetBackgroundContainerId(bool locked) {
   return locked ? internal::kShellWindowId_LockScreenBackgroundContainer :
                   internal::kShellWindowId_DesktopBackgroundContainer;
 }
 
 void DesktopBackgroundController::UpdateWallpaper() {
   current_wallpaper_.reset(NULL);
   current_default_wallpaper_path_ = base::FilePath();
   current_default_wallpaper_resource_id_ = -1;
   ash::Shell::GetInstance()->user_wallpaper_delegate()->
-      UpdateWallpaper();
+      UpdateWallpaper(true /* clear cache */);
 }
 
 // static
 gfx::Size DesktopBackgroundController::GetMaxDisplaySizeInNative() {
   int width = 0;
   int height = 0;
   std::vector<gfx::Display> displays = Shell::GetScreen()->GetAllDisplays();
   internal::DisplayManager* display_manager =
       Shell::GetInstance()->display_manager();
 
   for (std::vector<gfx::Display>::iterator iter = displays.begin();
        iter != displays.end(); ++iter) {
     // Don't use size_in_pixel because we want to use the native pixel size.
     gfx::Size size_in_pixel =
         display_manager->GetDisplayInfo(iter->id()).bounds_in_native().size();
     if (iter->rotation() == gfx::Display::ROTATE_90 ||
         iter->rotation() == gfx::Display::ROTATE_270) {
       size_in_pixel = gfx::Size(size_in_pixel.height(), size_in_pixel.width());
     }
     width = std::max(size_in_pixel.width(), width);
     height = std::max(size_in_pixel.height(), height);
   }
   return gfx::Size(width, height);
 }
 
 }  // namespace ash