Have ExtensionHost use TabContents instead of RenderViewHost. Try #3.

chrome/browser/ui/views/extensions/extension_dialog.cc

 // Copyright (c) 2011 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.
 
 #include "chrome/browser/ui/views/extensions/extension_dialog.h"
 
 #include "chrome/browser/extensions/extension_host.h"
 #include "chrome/browser/extensions/extension_process_manager.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/views/extensions/extension_dialog_observer.h"
 #include "chrome/browser/ui/views/window.h"  // CreateViewsWindow
 #include "chrome/common/chrome_notification_types.h"
 #include "content/browser/renderer_host/render_view_host.h"
 #include "content/browser/renderer_host/render_widget_host_view.h"
+#include "content/browser/tab_contents/tab_contents.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_source.h"
 #include "googleurl/src/gurl.h"
 #include "views/widget/widget.h"
 
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/frame/bubble_window.h"
 #endif
 
 namespace {
@@ skipping 39 matching lines @@
     ExtensionDialogObserver* observer) {
   CHECK(browser);
   ExtensionHost* host = CreateExtensionHost(url, browser);
   if (!host)
     return NULL;
   host->set_associated_tab_contents(tab_contents);
 
   ExtensionDialog* dialog = new ExtensionDialog(host, observer);
   dialog->InitWindow(browser, width, height);
   // Ensure the DOM JavaScript can respond immediately to keyboard shortcuts.
-  host->render_view_host()->view()->Focus();
+  host->host_contents()->Focus();
   return dialog;
 }
 
 // static
 ExtensionHost* ExtensionDialog::CreateExtensionHost(const GURL& url,
                                                     Browser* browser) {
   ExtensionProcessManager* manager =
       browser->profile()->GetExtensionProcessManager();
   DCHECK(manager);
   if (!manager)
@@ skipping 73 matching lines @@
       // If we aren't the host of the popup, then disregard the notification.
       if (content::Details<ExtensionHost>(host()) != details)
         return;
       Close();
       break;
     default:
       NOTREACHED() << L"Received unexpected notification";
       break;
   }
 }