Extension settings API: send ACTION_UPDATE rather than ACTION_ADD when a

chrome/browser/extensions/syncable_extension_settings_storage.cc

Index: chrome/browser/extensions/syncable_extension_settings_storage.cc
diff --git a/chrome/browser/extensions/syncable_extension_settings_storage.cc b/chrome/browser/extensions/syncable_extension_settings_storage.cc
index 8ec5d178941d6d24a1bd4d8bcc4cdbdc46492e49..cf5776665e98e1ca4e782320d7d6b9672c2f7f89 100644
--- a/chrome/browser/extensions/syncable_extension_settings_storage.cc
+++ b/chrome/browser/extensions/syncable_extension_settings_storage.cc
@@ -174,7 +174,10 @@ SyncError SyncableExtensionSettingsStorage::OverwriteLocalSettingsWithSync(
       scoped_ptr<Value> sync_value(orphaned_sync_value);
       Value* local_value = NULL;
       settings.GetWithoutPathExpansion(*it, &local_value);
-      if (!sync_value->Equals(local_value)) {
+      if (sync_value->Equals(local_value)) {
+        // Sync and local values are the same, no changes to send.
+        synced_keys_.insert(*it);
+      } else {
         // Sync value is different, update local setting with new value.
         changes.push_back(
             ExtensionSettingSyncData(