Annotates functions returning retained objects.

ios/public/provider/chrome/browser/test_updatable_resource_provider.mm

 // Copyright 2015 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.
 
 #import "ios/public/provider/chrome/browser/test_updatable_resource_provider.h"
 
 #include "base/logging.h"
 #include "base/mac/scoped_nsobject.h"
 
 #pragma mark - TestUpdatabeResourceDescriptor
@@ skipping 79 matching lines @@
 
 namespace ios {
 
 NSString* TestUpdatableResourceProvider::GetUpdateNotificationName() {
   return @"ResourceUpdatedTest";
 }
 
 id<UpdatableResourceBridge>
 TestUpdatableResourceProvider::CreateUpdatableResource(
     NSString* resource_identifier,
-    id<UpdatableResourceDelegate> delegate) {
+    id<UpdatableResourceDelegate> delegate) NS_RETURNS_RETAINED {
   NSString* path =
       [NSString stringWithFormat:@"%@/gm-config/ANY/%@",
                                  [[NSBundle mainBundle] resourcePath],
                                  resource_identifier];
   return [[TestUpdatableResource alloc] initWithDelegate:delegate plist:path];
 }
 
 }  // namespace ios