Fix wallpaper change to a random one when user first click "set wallpaper".

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 554d828f35656cd0fc33f9a628d8ccf48f11ee6e..26801e97a4dcc6abbc340bddc06d682d61c6d78d 100644
--- a/chrome/browser/chromeos/login/mock_user_manager.h
+++ b/chrome/browser/chromeos/login/mock_user_manager.h
@@ -33,8 +33,8 @@ 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_METHOD0(GetUserWallpaperIndex, int(void));
+  MOCK_METHOD1(SaveUserWallpaperIndex, void(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&));