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

chrome_frame/bho.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_BHO_H_
 #define CHROME_FRAME_BHO_H_
 
 #include <string>
 
 #include <atlbase.h>
 #include <atlcom.h>
 #include <exdisp.h>
 #include <exdispid.h>
 #include <mshtml.h>
 #include <shdeprecated.h>
 
+#include "base/lazy_instance.h"
+#include "base/thread_local.h"
 #include "chrome_tab.h"  // NOLINT
 #include "chrome_frame/resource.h"
 #include "grit/chrome_frame_resources.h"
 
 class PatchHelper {
  public:
   enum State { UNKNOWN, PATCH_IBROWSER, PATCH_IBROWSER_OK, PATCH_PROTOCOL };
   PatchHelper() : state_(UNKNOWN) {
   }
 
@@ skipping 51 matching lines @@
   // It also sends contents of the meta tag as an argument. IEFrame
   // handles this in IBrowserService::OnHttpEquiv.  So this allows
   // us to sniff the META tag by simply patching it. The renderer
   // switching can be achieved by cancelling original navigation
   // and issuing a new one using IWebBrowser2->Navigate2.
   static HRESULT STDMETHODCALLTYPE OnHttpEquiv(
       IBrowserService_OnHttpEquiv_Fn original_httpequiv,
       IBrowserService* browser, IShellView* shell_view, BOOL done,
       VARIANT* in_arg, VARIANT* out_arg);
 
+  std::string referrer() const {
+    return referrer_;
+  }
+
+  // Returns the Bho instance for the current thread. This is returned from
+  // TLS.
+  static Bho* GetCurrentThreadBhoInstance();
+
  protected:
   bool PatchProtocolHandler(const CLSID& handler_clsid);
   static bool HasSubFrames(IWebBrowser2* web_browser2);
   static HRESULT SwitchRenderer(IWebBrowser2* web_browser2,
       IBrowserService* browser, IShellView* shell_view,
       const wchar_t* meta_tag);
+  std::string referrer_;
 
+  static base::LazyInstance<base::ThreadLocalPointer<Bho> >
+      bho_current_thread_instance_;
   static _ATL_FUNC_INFO kBeforeNavigate2Info;
 };
 
 // Add Bho to class library table so IE can CoCreate it.
 OBJECT_ENTRY_AUTO(CLSID_ChromeFrameBHO, Bho);
 
 #endif  // CHROME_FRAME_BHO_H_