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

chrome/browser/extensions/api/tabs/ash_panel_contents.cc

Index: chrome/browser/extensions/api/tabs/ash_panel_contents.cc
diff --git a/chrome/browser/extensions/api/tabs/ash_panel_contents.cc b/chrome/browser/extensions/api/tabs/ash_panel_contents.cc
index ac891e49e9d7eee87f9dbe7becac729d224fac7a..be3adcea78fe8f863f4bb4e214b131238dafa1d1 100644
--- a/chrome/browser/extensions/api/tabs/ash_panel_contents.cc
+++ b/chrome/browser/extensions/api/tabs/ash_panel_contents.cc
@@ -16,6 +16,7 @@
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/site_instance.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/browser/web_contents_source.h"
 #include "extensions/browser/app_window/native_app_window.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/permissions/api_permission.h"
@@ -39,6 +40,8 @@ void AshPanelContents::Initialize(content::BrowserContext* context,
   web_contents_.reset(
       content::WebContents::Create(content::WebContents::CreateParams(
           context, content::SiteInstance::CreateForURL(context, url_))));
+  WebContentsSource::CreateForWebContentsAndLocation(web_contents_.get(),
+                                                     FROM_HERE);
 
   // Needed to give the web contents a Window ID. Extension APIs expect web
   // contents to have a Window ID. Also required for FaviconDriver to correctly