When Chrome hands off a URL to be opened by the external host by the ViewHost...

chrome_frame/chrome_frame_automation.h

 // Copyright (c) 2009 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_FRAME_CHROME_FRAME_AUTOMATION_H_
 #define CHROME_FRAME_CHROME_FRAME_AUTOMATION_H_
 
 #include <atlbase.h>
 #include <atlwin.h>
 #include <string>
@@ skipping 172 matching lines @@
 
   // Called from UI thread.
   virtual bool Initialize(ChromeFrameDelegate* chrome_frame_delegate,
                           int automation_server_launch_timeout,
                           bool perform_version_check,
                           const std::wstring& profile_name,
                           const std::wstring& extra_chrome_arguments,
                           bool incognito);
   void Uninitialize();
 
-  virtual bool InitiateNavigation(const std::string& url, bool is_privileged);
+  virtual bool InitiateNavigation(const std::string& url,
+                                  const std::string& referrer,
+                                  bool is_privileged);
   virtual bool NavigateToIndex(int index);
   bool ForwardMessageFromExternalHost(const std::string& message,
                                       const std::string& origin,
                                       const std::string& target);
   bool SetProxySettings(const std::string& json_encoded_proxy_settings);
 
   virtual void SetEnableExtensionAutomation(bool enable_automation);
 
   void FindInPage(const std::wstring& search_string,
                   FindInPageDirection forward,
@@ skipping 97 matching lines @@
   //                                           ChromeFrameDelegate::Something,
   //                                           param1,
   //                                           param2));
   void CallDelegate(const tracked_objects::Location& from_here,
                     Task* delegate_task);
   // The workhorse method called in main/GUI thread which is going to
   // execute ChromeFrameDelegate method encapsulated in delegate_task.
   void CallDelegateImpl(Task* delegate_task);
 
   HWND chrome_window() const { return chrome_window_; }
-  void BeginNavigate(const GURL& url);
+  void BeginNavigate(const GURL& url, const GURL& referrer);
   void BeginNavigateCompleted(AutomationMsg_NavigationResponseValues result);
 
   // Helpers
   void ReportNavigationError(AutomationMsg_NavigationResponseValues error_code,
                              const std::string& url);
 
   bool is_initialized() const {
     return init_state_ == INITIALIZED;
   }
 
@@ skipping 28 matching lines @@
   InitializationState init_state_;
   bool use_chrome_network_;
   bool handle_top_level_requests_;
   ProxyFactory* proxy_factory_;
   int tab_handle_;
   // Only used if we attach to an existing tab.
   intptr_t external_tab_cookie_;
 };
 
 #endif  // CHROME_FRAME_CHROME_FRAME_AUTOMATION_H_