Use content::Referrer to pass around referrers in the plugin code

content/renderer/npapi/webplugin_delegate_proxy.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_RENDERER_NPAPI_WEBPLUGIN_DELEGATE_PROXY_H_
 #define CONTENT_RENDERER_NPAPI_WEBPLUGIN_DELEGATE_PROXY_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 119 matching lines @@
   WebPluginResourceClient* CreateSeekableResourceClient(
       unsigned long resource_id,
       int range_request_id) override;
   void FetchURL(unsigned long resource_id,
                 int notify_id,
                 const GURL& url,
                 const GURL& first_party_for_cookies,
                 const std::string& method,
                 const char* buf,
                 unsigned int len,
-                const GURL& referrer,
+                const Referrer& referrer,
                 bool notify_redirects,
                 bool is_plugin_src_load,
                 int origin_pid,
                 int render_frame_id,
                 int render_view_id) override;
 
   gfx::PluginWindowHandle GetPluginWindowHandle();
 
  protected:
   friend class base::DeleteHelper<WebPluginDelegateProxy>;
@@ skipping 158 matching lines @@
 
   // The url of the main frame hosting the plugin.
   GURL page_url_;
 
   DISALLOW_COPY_AND_ASSIGN(WebPluginDelegateProxy);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_NPAPI_WEBPLUGIN_DELEGATE_PROXY_H_