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

chrome/browser/chromeos/login/mock_user_manager.h

Index: chrome/browser/chromeos/login/mock_user_manager.h
diff --git a/chrome/browser/chromeos/login/mock_user_manager.h b/chrome/browser/chromeos/login/mock_user_manager.h
index 48482540aefac572ffeff423134782530e5f8537..64e358e9b4ad414b16ed4574a0fd1a8251c9ee66 100644
--- a/chrome/browser/chromeos/login/mock_user_manager.h
+++ b/chrome/browser/chromeos/login/mock_user_manager.h
@@ -34,6 +34,8 @@ class MockUserManager : public UserManager {
                                          User::OAuthTokenStatus));
   MOCK_METHOD2(SaveUserDisplayEmail, void(const std::string&,
                                           const std::string&));
+  MOCK_METHOD1(GetUserWallpaper, int(const std::string&));
+  MOCK_METHOD2(SaveWallpaperDefaultIndex, void(const std::string&, int));
   MOCK_CONST_METHOD1(GetUserDisplayEmail, std::string(const std::string&));
   MOCK_METHOD2(SaveUserDefaultImageIndex, void(const std::string&, int));
   MOCK_METHOD2(SaveUserImage, void(const std::string&, const SkBitmap&));