Change GuestViewInternalCreateGuestFunction to create the guest view using the

extensions/browser/guest_view/guest_view_base.cc

 // Copyright 2014 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 "extensions/browser/guest_view/guest_view_base.h"
 
 #include "base/lazy_instance.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
@@ skipping 103 matching lines @@
   CHECK(feature);
 
   extensions::ProcessMap* process_map =
       extensions::ProcessMap::Get(browser_context());
   CHECK(process_map);
 
   const extensions::Extension* embedder_extension =
       extensions::ExtensionRegistry::Get(browser_context_)
           ->enabled_extensions()
           .GetByID(embedder_extension_id);
+  // Ok for |embedder_extension| to be NULL, the embedder might be WebUI.
+
+  CHECK(embedder_web_contents);
   int embedder_process_id =
       embedder_web_contents->GetRenderProcessHost()->GetID();
 
   extensions::Feature::Availability availability =
       feature->IsAvailableToContext(
           embedder_extension,
           process_map->GetMostLikelyContextType(embedder_extension,
                                                 embedder_process_id),
           embedder_web_contents->GetLastCommittedURL());
   if (!availability.is_available()) {
@@ skipping 311 matching lines @@
                       guest_web_contents);
   callback.Run(guest_web_contents);
 }
 
 // static
 void GuestViewBase::RegisterGuestViewTypes() {
   extensions::ExtensionsAPIClient::Get()->RegisterGuestViewTypes();
 }
 
 }  // namespace extensions