In ~ExtensionHost, close swapped-out RenderViews referring to this extension.

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 145 matching lines @@
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_UNLOADED,
                  content::Source<Profile>(profile_));
 }
 
 ExtensionHost::~ExtensionHost() {
   if (extension_host_type_ == chrome::VIEW_TYPE_EXTENSION_BACKGROUND_PAGE &&
       extension_ && BackgroundInfo::HasLazyBackgroundPage(extension_)) {
     UMA_HISTOGRAM_LONG_TIMES("Extensions.EventPageActiveTime",
                              since_created_.Elapsed());
   }
+  // Clear the extension's renderer process out from any WebContents
+  // that might have it in their back history.
+  // TODO(jyasskin): Remove this hack by making extension reloading
+  // wait for renderer shutdown.
+  content::NotificationService::current()->Notify(
+      content::NOTIFICATION_RENDERER_PROCESS_CLOSING,
+      content::Source<content::RenderProcessHost>(render_process_host()),
+      content::NotificationService::NoDetails());
+
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_EXTENSION_HOST_DESTROYED,
       content::Source<Profile>(profile_),
       content::Details<ExtensionHost>(this));
   ProcessCreationQueue::GetInstance()->Remove(this);
 }
 
 void ExtensionHost::CreateView(Browser* browser) {
 #if defined(TOOLKIT_VIEWS)
   view_.reset(new ExtensionViewViews(this, browser));
@@ skipping 448 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