Use a direct include of strings headers in chrome/renderer/.

chrome/renderer/web_apps.h

 // Copyright (c) 2012 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 CHROME_RENDERER_WEB_APPS_H_
 #define CHROME_RENDERER_WEB_APPS_H_
 
 #include <string>
 #include <vector>
 
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "ui/gfx/size.h"
 
 namespace WebKit {
 class WebFrame;
 }
 
 struct WebApplicationInfo;
 
 namespace web_apps {
 
@@ skipping 14 matching lines @@
 // web_app will have manifest_url set and nothing else. The caller must fetch
 // this URL and pass the result to ParseWebAppFromDefinitionFile() for further
 // processing.
 bool ParseWebAppFromWebDocument(WebKit::WebFrame* frame,
                                 WebApplicationInfo* web_app,
                                 string16* error);
 
 }  // namespace web_apps
 
 #endif  // CHROME_RENDERER_WEB_APPS_H_