Track where WebContents are created in order to better understand issue.

extensions/browser/guest_view/web_view/web_view_guest.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/web_view/web_view_guest.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/browsing_data/storage_partition_http_cache_data_remover.h"
@@ skipping 13 matching lines @@
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/resource_request_details.h"
 #include "content/public/browser/site_instance.h"
 #include "content/public/browser/storage_partition.h"
 #include "content/public/browser/user_metrics.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
+#include "content/public/browser/web_contents_source.h"
 #include "content/public/common/media_stream_request.h"
 #include "content/public/common/page_zoom.h"
 #include "content/public/common/result_codes.h"
 #include "content/public/common/stop_find_action.h"
 #include "content/public/common/url_constants.h"
 #include "extensions/browser/api/declarative/rules_registry_service.h"
 #include "extensions/browser/api/extensions_api_client.h"
 #include "extensions/browser/api/guest_view/web_view/web_view_internal_api.h"
 #include "extensions/browser/api/web_request/web_request_api.h"
 #include "extensions/browser/extension_system.h"
@@ skipping 304 matching lines @@
     // Create the SiteInstance in a new BrowsingInstance, which will ensure
     // that webview tags are also not allowed to send messages across
     // different partitions.
     guest_site_instance = content::SiteInstance::CreateForURL(
         owner_render_process_host->GetBrowserContext(), guest_site);
   }
   WebContents::CreateParams params(
       owner_render_process_host->GetBrowserContext(),
       guest_site_instance);
   params.guest_delegate = this;
-  callback.Run(WebContents::Create(params));
+  WebContents* web_contents = WebContents::Create(params);
+  WebContentsSource::CreateForWebContentsAndLocation(web_contents, FROM_HERE);
+  callback.Run(web_contents);
 }
 
 void WebViewGuest::DidAttachToEmbedder() {
   ApplyAttributes(*attach_params());
 }
 
 void WebViewGuest::DidDropLink(const GURL& url) {
   scoped_ptr<base::DictionaryValue> args(new base::DictionaryValue());
   args->SetString(guest_view::kUrl, url.spec());
   DispatchEventToView(
@@ skipping 1124 matching lines @@
     scoped_ptr<base::DictionaryValue> args(new base::DictionaryValue());
     DispatchEventToView(
         new GuestViewEvent(webview::kEventExitFullscreen, args.Pass()));
   }
   // Since we changed fullscreen state, sending a Resize message ensures that
   // renderer/ sees the change.
   web_contents()->GetRenderViewHost()->GetWidget()->WasResized();
 }
 
 }  // namespace extensions