Use a direct include of strings headers in chrome/browser/ui/webui/, part 1.

chrome/browser/ui/webui/extensions/install_extension_handler.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_BROWSER_UI_WEBUI_EXTENSIONS_INSTALL_EXTENSION_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_EXTENSIONS_INSTALL_EXTENSION_HANDLER_H_
 
 #include "base/files/file_path.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "base/values.h"
 #include "content/public/browser/web_ui_message_handler.h"
 
 namespace content {
 class WebUIDataSource;
 }
 
 // Handles installing an extension when its file is dragged onto the page.
 class InstallExtensionHandler : public content::WebUIMessageHandler {
  public:
@@ skipping 25 matching lines @@
 
   // The path to the file that will be installed when HandleInstallMessage() is
   // called.
   base::FilePath file_to_install_;
   base::string16 file_display_name_;
 
   DISALLOW_COPY_AND_ASSIGN(InstallExtensionHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_EXTENSIONS_INSTALL_EXTENSION_HANDLER_H_