Use default wallpaper when the logged in user didn't have saved wallpaper in LocalState

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 a5df44fcb9ef512bcd6d00c1f44e42ad34c7b7fd..ee4aaa7f16693a7cb3ef50ed89433037edc95731 100644
--- a/chrome/browser/chromeos/login/user_manager_impl.cc
+++ b/chrome/browser/chromeos/login/user_manager_impl.cc
@@ -939,19 +939,31 @@ void UserManagerImpl::MigrateWallpaperData() {
     const DictionaryValue* user_wallpapers =
           local_state->GetDictionary(kUserWallpapers);
     int index;
-    if (user_wallpapers) {
-      const UserList& users = GetUsers();
-      for (UserList::const_iterator it = users.begin();
-           it != users.end();
-           ++it) {
-        std::string username = (*it)->email();
-        if (user_wallpapers->GetIntegerWithoutPathExpansion((username),
-            &index)) {
-          DictionaryPrefUpdate prefs_wallpapers_update(local_state,
-                                                       kUserWallpapers);
-          prefs_wallpapers_update->RemoveWithoutPathExpansion(username, NULL);
-          SaveUserWallpaperProperties(username, User::DEFAULT, index);
-        }
+    const UserList& users = GetUsers();
+    for (UserList::const_iterator it = users.begin();
+         it != users.end();
+         ++it) {
+      std::string username = (*it)->email();
+      if (user_wallpapers->GetIntegerWithoutPathExpansion((username),
+          &index)) {
+        DictionaryPrefUpdate prefs_wallpapers_update(local_state,
+                                                     kUserWallpapers);
+        prefs_wallpapers_update->RemoveWithoutPathExpansion(username, NULL);
+        SaveUserWallpaperProperties(username, User::DEFAULT, index);
+      } else {
+        // Before M20, wallpaper index is not saved into LocalState unless user
+        // specifically sets a wallpaper. After M20, the default wallpaper index
+        // is saved to LocalState as soon as a new user login. When migrating
+        // wallpaper index from M20 to M21, we only migrate data that is in
+        // LocalState. This cause a problem when users login on a M20 device and
+        // then update the device to M21. The default wallpaper index failed to
+        // migrate because it was not saved into LocalState. Then we assume that
+        // all users have index saved in LocalState in M21. This is not true and
+        // it results an empty wallpaper for those users as described in
+        // cr/130685. So here we use default wallpaper for users that exist in
+        // user list but does not have an index saved in LocalState.
+        SaveUserWallpaperProperties(username, User::DEFAULT,
+                                    ash::GetDefaultWallpaperIndex());
       }
     }
   }
@@ -1027,17 +1039,15 @@ void UserManagerImpl::GetUserWallpaperProperties(const std::string& username,
   if (!username.empty()) {
     const DictionaryValue* user_wallpapers = g_browser_process->local_state()->
         GetDictionary(UserManager::kUserWallpapersProperties);
-    if (user_wallpapers) {

[Nikita (slow), 2012/06/05 08:07:17]

Why this check is removed?
DCHECK(user_wallpapers)?

[bshe, 2012/06/08 15:22:52]

It seem this check is always true if we register the pref service. So I removed
it.

-      base::DictionaryValue* wallpaper_properties;
-      if (user_wallpapers->GetDictionaryWithoutPathExpansion(
-          username,
-          &wallpaper_properties)) {
-        *type = User::UNKNOWN;
-        *index = ash::GetDefaultWallpaperIndex();
-        wallpaper_properties->GetInteger(kWallpaperTypeNodeName,
-                                         reinterpret_cast<int*>(type));
-        wallpaper_properties->GetInteger(kWallpaperIndexNodeName, index);
-      }
+    base::DictionaryValue* wallpaper_properties;
+    if (user_wallpapers->GetDictionaryWithoutPathExpansion(
+        username,
+        &wallpaper_properties)) {
+      *type = User::UNKNOWN;
+      *index = ash::GetDefaultWallpaperIndex();
+      wallpaper_properties->GetInteger(kWallpaperTypeNodeName,
+                                       reinterpret_cast<int*>(type));
+      wallpaper_properties->GetInteger(kWallpaperIndexNodeName, index);
     }
   }
 }