Extension settings API: send ACTION_UPDATE rather than ACTION_ADD when a

chrome/browser/extensions/syncable_extension_settings_storage.cc

 // Copyright (c) 2011 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.
 
 #include "chrome/browser/extensions/syncable_extension_settings_storage.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/extensions/extension_settings_sync_util.h"
 #include "chrome/browser/sync/api/sync_data.h"
 #include "chrome/browser/sync/protocol/extension_setting_specifics.pb.h"
@@ skipping 156 matching lines @@
   scoped_ptr<DictionaryValue> new_sync_state(sync_state.DeepCopy());
 
   ExtensionSettingSyncDataList changes;
   for (DictionaryValue::key_iterator it = settings.begin_keys();
       it != settings.end_keys(); ++it) {
     Value* orphaned_sync_value = NULL;
     if (new_sync_state->RemoveWithoutPathExpansion(*it, &orphaned_sync_value)) {
       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(
                 SyncChange::ACTION_UPDATE,
                 extension_id_,
                 *it,
                 sync_value.release()));
       }
     } else {
       // Not synced, delete local setting.
@@ skipping 241 matching lines @@
   if (result.HasError()) {
     return SyncError(
         FROM_HERE,
         std::string("Error pushing sync remove to local settings: ") +
             result.GetError(),
         syncable::EXTENSION_SETTINGS);
   }
   changes->AppendChange(key, old_value, NULL);
   return SyncError();
 }