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

chrome/browser/chromeos/login/user_manager.h

 // Copyright (c) 2012 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_USER_MANAGER_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_USER_MANAGER_H_
 #pragma once
 
 #include <string>
 
@@ skipping 118 matching lines @@
   // Ignored If there is no such user.
   virtual void SaveUserDisplayEmail(const std::string& username,
                                     const std::string& display_email) = 0;
 
   // Returns the display email for user |username| if it is known (was
   // previously set by a |SaveUserDisplayEmail| call).
   // Otherwise, returns |username| itself.
   virtual std::string GetUserDisplayEmail(
       const std::string& username) const = 0;
 
-  // 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.
-  virtual int GetUserWallpaper(const std::string& username) = 0;
+  // Returns the index of the default wallpapers saved in local state for login
+  // user if it is known (was previousely set by |SaveWallpaperToLocalState|
+  // call). Otherwise, returns a randomly generated index.
+  virtual int GetUserWallpaperIndex() = 0;
 
-  // Sets user wallpaper to the default wallpaper with index |wallpaper_index|,
-  // updates Local State.
-  virtual void SaveWallpaperDefaultIndex(const std::string& username,
-                                         int wallpaper_index) = 0;
+  // Save the index |wallpaper_index| of the default wallpapers selected by
+  // current user to Local State.
+  virtual void SaveUserWallpaperIndex(int wallpaper_index) = 0;
 
   // Sets user image to the default image with index |image_index|, sends
   // LOGIN_USER_IMAGE_CHANGED notification and updates Local State.
   virtual void SaveUserDefaultImageIndex(const std::string& username,
                                          int image_index) = 0;
 
   // Saves image to file, sends LOGIN_USER_IMAGE_CHANGED notification and
   // updates Local State.
   virtual void SaveUserImage(const std::string& username,
                              const SkBitmap& image) = 0;
@@ skipping 44 matching lines @@
   virtual void NotifyLocalStateChanged() = 0;
 
   // Returns the result of the last successful profile image download, if any.
   // Otherwise, returns an empty bitmap.
   virtual const SkBitmap& DownloadedProfileImage() const = 0;
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_USER_MANAGER_H_