Invalidate all wallpaper cache if display configuration changed

chrome/browser/ui/ash/user_wallpaper_delegate_win.cc

 // Copyright (c) 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/desktop_background/user_wallpaper_delegate.h"
 
 #include "ash/desktop_background/desktop_background_controller.h"
 #include "ash/shell.h"
 #include "ash/wm/window_animations.h"
 #include "base/basictypes.h"
@@ skipping 26 matching lines @@
   virtual int GetAnimationDurationOverride() OVERRIDE {
     // Return 0 to select the default.
     return 0;
   }
 
   virtual void SetAnimationDurationOverride(
       int animation_duration_in_ms) OVERRIDE {
     NOTIMPLEMENTED();
   }
 
-  virtual void UpdateWallpaper() OVERRIDE {
+  virtual void UpdateWallpaper(bool clear_cache) OVERRIDE {
     SkBitmap bitmap;
     bitmap.setConfig(SkBitmap::kARGB_8888_Config, 16, 16);
     bitmap.allocPixels();
     bitmap.eraseARGB(255, kBackgroundRed, kBackgroundGreen, kBackgroundBlue);
 #if !defined(NDEBUG)
     // In debug builds we generate a simple pattern that allows visually
     // notice if transparency is broken.
     {
       SkAutoLockPixels alp(bitmap);
       *bitmap.getAddr32(0,0) = SkColorSetRGB(0, 0, 0);
     }
 #endif
     gfx::ImageSkia wallpaper = gfx::ImageSkia::CreateFrom1xBitmap(bitmap);
     ash::Shell::GetInstance()->desktop_background_controller()->
         SetCustomWallpaper(wallpaper, ash::WALLPAPER_LAYOUT_TILE);
   }
 
   virtual void InitializeWallpaper() OVERRIDE {
-    UpdateWallpaper();
+    UpdateWallpaper(false);
   }
 
   virtual void OpenSetWallpaperPage() OVERRIDE {
   }
 
   virtual bool CanOpenSetWallpaperPage() OVERRIDE {
     return false;
   }
 
   virtual void OnWallpaperAnimationFinished() OVERRIDE {
   }
 
   virtual void OnWallpaperBootAnimationFinished() OVERRIDE {
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(UserWallpaperDelegate);
 };
 
 }  // namespace
 
 ash::UserWallpaperDelegate* CreateUserWallpaperDelegate() {
   return new UserWallpaperDelegate();
 }