Enable user change background image in settings page in Aura build.

chrome/browser/chromeos/login/user_manager.h

Index: chrome/browser/chromeos/login/user_manager.h
diff --git a/chrome/browser/chromeos/login/user_manager.h b/chrome/browser/chromeos/login/user_manager.h
index 6e70d7cccc4a2a00169a9fe6400573e316668955..dcef6a81d0742bf5139abbdf291d931a8702a96e 100644
--- a/chrome/browser/chromeos/login/user_manager.h
+++ b/chrome/browser/chromeos/login/user_manager.h
@@ -99,6 +99,16 @@ class UserManager : public ProfileDownloaderDelegate,
   // Otherwise, returns |username| itself.
   std::string GetUserDisplayEmail(const std::string& username) const;
 
+  // Returns the index of the default wallpapers saved in local state for user
+  // |username| if it is known (was previousely set by
+  // |SaveWallpaperToLocalState| call).
+  // Otherwise, returns default wallpaper index.
+  int GetUserWallpaper(const std::string& username);
+
+  // Stores index to the user choosed defautl wallpaper in local state.

[flackr, 2012/03/06 17:16:49]

Sets the user wallpaper to the default wallpaper with index |wallpaper_index|,
sends WALLPAPER_CHANGED notification and updates Local State.

Of course replace WALLPAPER_CHANGED with the real notification name :-)

[bshe, 2012/03/06 19:56:16]

Done.

+  void SaveWallpaperToLocalState(const std::string& username,
+                                 int wallpaper_index);

[flackr, 2012/03/06 17:16:49]

As with SaveUserDefaultImageIndex below, call this SaveWallpaperDefaultIndex,
you can mention local state in comment.

[bshe, 2012/03/06 19:56:16]

Done.

+
   // Sets user image to the default image with index |image_index|, sends
   // LOGIN_USER_IMAGE_CHANGED notification and updates Local State.
   void SaveUserDefaultImageIndex(const std::string& username, int image_index);