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

chrome/browser/chromeos/login/user_manager_impl.cc

Index: chrome/browser/chromeos/login/user_manager_impl.cc
diff --git a/chrome/browser/chromeos/login/user_manager_impl.cc b/chrome/browser/chromeos/login/user_manager_impl.cc
index a5800a51771b635d33e3d4b982e0c2b4a06f7acd..0cc82d7c520f441de1cc888b172bdb7e8fcb6b80 100644
--- a/chrome/browser/chromeos/login/user_manager_impl.cc
+++ b/chrome/browser/chromeos/login/user_manager_impl.cc
@@ -907,29 +907,46 @@ void UserManagerImpl::SetInitialUserImage(const std::string& username) {
   SaveUserDefaultImageIndex(username, image_id);
 }
 
-int UserManagerImpl::GetUserWallpaper(const std::string& username) {
+int UserManagerImpl::GetUserWallpaperIndex() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
+  // If at login screen or logged in as a guest/incognito user, then use the
+  // randomly generated wallpaper.
+  if (IsLoggedInAsGuest() || !IsUserLoggedIn())

[Nikita (slow), 2012/03/25 21:24:08]

+ IsCurrentUserEphemeral()

In fact you should remove IsLoggedInAsGuest() and add only

if (IsCurrentUserEphemeral() || !IsUserLoggedIn())

IsCurrentUserEphemeral will be true for Demo/Guest/normal users when Ephemeral
policy is enabled / stub user.

Obviously this will block testing change of wallpaper on desktop (where stub
user is normally used) but that should be fixed separately.

+    return ash::GetGuestWallpaperIndex();
+
+  const chromeos::User& user = GetLoggedInUser();
+  std::string username = user.email();
+  DCHECK(!username.empty());
+
   PrefService* local_state = g_browser_process->local_state();
   const DictionaryValue* user_wallpapers =
       local_state->GetDictionary(UserManager::kUserWallpapers);
   int index = ash::GetDefaultWallpaperIndex();
-  user_wallpapers->GetIntegerWithoutPathExpansion(username,
-                                                  &index);
+  if (!user_wallpapers->GetIntegerWithoutPathExpansion(username, &index))
+    SaveUserWallpaperIndex(index);
+
+  DCHECK(index >=0 && index < ash::GetWallpaperCount());
   return index;
 }
 
-void UserManagerImpl::SaveWallpaperDefaultIndex(const std::string& username,
-                                                int wallpaper_index) {
+void UserManagerImpl::SaveUserWallpaperIndex(int wallpaper_index) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  // If at login screen or logged in as a guest/incognito user, then return.
+  // Guest/incognito user can not change wallpaper according to chromium-os
+  // issue 26900.
+  if (IsLoggedInAsGuest() || !IsUserLoggedIn())

[Nikita (slow), 2012/03/25 21:24:08]

Change IsLoggedInAsGuest() to IsCurrentUserEphemeral() so that ephemeral and
demo users are handled too.

If ephemeral user policy is enabed - no changes should be made to LocalState as
user home will be removed on sign out. All changes should reside in memory.
Demo user / guest user is a variant of ephemeral users.

+    return;
+
+  const chromeos::User& user = GetLoggedInUser();
+  std::string username = user.email();
+  DCHECK(!username.empty());
 
   PrefService* local_state = g_browser_process->local_state();
   DictionaryPrefUpdate wallpapers_update(local_state,
                                          UserManager::kUserWallpapers);
   wallpapers_update->SetWithoutPathExpansion(username,
       new base::FundamentalValue(wallpaper_index));
-  ash::Shell::GetInstance()->desktop_background_controller()->
-      OnDesktopBackgroundChanged();
 }
 
 void UserManagerImpl::SetUserImage(const std::string& username,