Make the UI an observer of downloads.

chrome/browser/extensions/extension_host.cc

 // 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.
 
 #include "chrome/browser/extensions/extension_host.h"
 
 #include <list>
 
 #include "base/bind.h"
 #include "base/memory/singleton.h"
@@ skipping 395 matching lines @@
   // TODO(mpcomplete): is this check really necessary?
   if (extension_host_type_ == chrome::VIEW_TYPE_EXTENSION_POPUP ||
       extension_host_type_ == chrome::VIEW_TYPE_EXTENSION_DIALOG ||
       extension_host_type_ == chrome::VIEW_TYPE_EXTENSION_BACKGROUND_PAGE ||
       extension_host_type_ == chrome::VIEW_TYPE_EXTENSION_INFOBAR ||
       extension_host_type_ == chrome::VIEW_TYPE_PANEL) {
     Close();
   }
 }
 
-void ExtensionHost::OnStartDownload(
-    content::WebContents* source, content::DownloadItem* download) {
-  // If |source| is in the context of a Browser, show the DownloadShelf on that
-  // Browser.
-  if (!view() || !view()->browser())
-    return;
-  static_cast<content::WebContentsDelegate*>(view()->browser())->
-    OnStartDownload(source, download);
-}
-
 void ExtensionHost::WillRunJavaScriptDialog() {
   ExtensionProcessManager* pm =
       ExtensionSystem::Get(profile_)->process_manager();
   if (pm)
     pm->IncrementLazyKeepaliveCount(extension());
 }
 
 void ExtensionHost::DidCloseJavaScriptDialog() {
   ExtensionProcessManager* pm =
       ExtensionSystem::Get(profile_)->process_manager();
@@ skipping 198 matching lines @@
       content::IsAudioMediaType(request.audio_type),
       content::IsVideoMediaType(request.video_type),
       &devices);
 
   // For tab capture device, we require the tabCapture permission.
   RequestMediaAccessPermissionHelper::AuthorizeRequest(
       devices, request, callback, extension(), false);
 }
 
 }  // namespace extensions