Invalidate all wallpaper cache if display configuration changed

chrome/browser/chromeos/login/wallpaper_manager.h

 // 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_LOGIN_WALLPAPER_MANAGER_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_WALLPAPER_MANAGER_H_
 
 #include <deque>
 #include <string>
 #include <vector>
@@ skipping 262 matching lines @@
 
   // Sets wallpaper to |wallpaper| (asynchronously with zero delay). If
   // |update_wallpaper| is false, skip change wallpaper but only update cache.
   void SetWallpaperFromImageSkia(const std::string& user_id,
                                  const gfx::ImageSkia& wallpaper,
                                  ash::WallpaperLayout layout,
                                  bool update_wallpaper);
 
   // Updates current wallpaper. It may switch the size of wallpaper based on the
   // current display's resolution. (asynchronously with zero delay)
-  void UpdateWallpaper();
+  void UpdateWallpaper(bool clear_cache);
 
   // Adds given observer to the list.
   void AddObserver(Observer* observer);
 
   // Removes given observer from the list.
   void RemoveObserver(Observer* observer);
 
  private:
   friend class TestApi;
   friend class WallpaperManagerBrowserTest;
@@ skipping 201 matching lines @@
   // All pending will be finally deleted on destroy.
   typedef std::vector<scoped_refptr<PendingWallpaper> > PendingList;
   PendingList loading_;
 
   DISALLOW_COPY_AND_ASSIGN(WallpaperManager);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_WALLPAPER_MANAGER_H_