Fix login visual hitch on chromebook

chrome/browser/chromeos/login/wallpaper_manager.h

Index: chrome/browser/chromeos/login/wallpaper_manager.h
diff --git a/chrome/browser/chromeos/login/wallpaper_manager.h b/chrome/browser/chromeos/login/wallpaper_manager.h
index 7e6c375852630e83ba564f1d48306bad56a1bb4d..8edd0b6c03fef7b7a67056e607dc5d95d914ab1c 100644
--- a/chrome/browser/chromeos/login/wallpaper_manager.h
+++ b/chrome/browser/chromeos/login/wallpaper_manager.h
@@ -63,14 +63,15 @@ class WallpaperManager: public system::TimezoneSettings::Observer,
   static WallpaperManager* Get();
 
   WallpaperManager();
+  virtual ~WallpaperManager();
+
+  // Indicates imminent shutdown, allowing the WallpaperManager to remove any
+  // observers it has registered.
+  void Shutdown();
 
   // Registers wallpaper manager preferences.
   static void RegisterPrefs(PrefServiceSimple* local_state);
 
-  // Adds PowerManagerClient and TimeZoneSettings observers. It needs to be
-  // added after PowerManagerClient has been initialized.
-  void AddObservers();
-
   // Loads wallpaper asynchronously if the current wallpaper is not the
   // wallpaper of logged in user.
   void EnsureLoggedInUserWallpaperLoaded();
@@ -158,8 +159,6 @@ class WallpaperManager: public system::TimezoneSettings::Observer,
   friend class WallpaperManagerBrowserTest;
   typedef std::map<std::string, gfx::ImageSkia> CustomWallpaperMap;
 
-  virtual ~WallpaperManager();
-
   // The number of wallpapers have loaded. For test only.
   int loaded_wallpapers() const { return loaded_wallpapers_; }