Use a direct include of strings headers in content/p*/.

content/public/browser/web_contents.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 CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
 #include "base/process_util.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "base/supports_user_data.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/page_navigator.h"
 #include "content/public/browser/save_page_type.h"
 #include "content/public/browser/web_ui.h"
 #include "ipc/ipc_sender.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/base/window_open_disposition.h"
 #include "ui/gfx/native_widget_types.h"
@@ skipping 440 matching lines @@
 
  private:
   // This interface should only be implemented inside content.
   friend class WebContentsImpl;
   WebContents() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_