Annotates functions returning retained objects.

ios/web/public/web_view_creation_util.h

 // Copyright 2014 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.
 
 #ifndef IOS_WEB_PUBLIC_WEB_VIEW_CREATION_UTIL_H_
 #define IOS_WEB_PUBLIC_WEB_VIEW_CREATION_UTIL_H_
 
 #import <CoreGraphics/CoreGraphics.h>
+#import <Foundation/NSObjCRuntime.h>
 
 @class WKWebView;
 
 namespace web {
 class BrowserState;
 
 // Returns a new WKWebView for displaying regular web content.
 // WKWebViewConfiguration object for resulting web view will be obtained from
 // the given |browser_state|.
 //
 // Preconditions for creation of a WKWebView:
 // 1) |browser_state| is not null.
 // 2) web::BrowsingDataPartition is synchronized.
 //
 // Note: Callers are responsible for releasing the returned WKWebView.
-WKWebView* CreateWKWebView(CGRect frame, BrowserState* browser_state);
+WKWebView* CreateWKWebView(CGRect frame,
+                           BrowserState* browser_state) NS_RETURNS_RETAINED;
 
 }  // web
 
 #endif  // IOS_WEB_PUBLIC_WEB_VIEW_CREATION_UTIL_H_