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

chrome/browser/chromeos/first_run/drive_first_run_controller.cc

Index: chrome/browser/chromeos/first_run/drive_first_run_controller.cc
diff --git a/chrome/browser/chromeos/first_run/drive_first_run_controller.cc b/chrome/browser/chromeos/first_run/drive_first_run_controller.cc
index 6a9b837aa1fb906d9326662a66668cf75044e752..b20d08ec89c8aabe38f539696ffcc8a0e4cc714b 100644
--- a/chrome/browser/chromeos/first_run/drive_first_run_controller.cc
+++ b/chrome/browser/chromeos/first_run/drive_first_run_controller.cc
@@ -34,6 +34,7 @@
 #include "content/public/browser/site_instance.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_observer.h"
+#include "content/public/browser/web_contents_source.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/common/extension.h"
@@ -214,6 +215,8 @@ void DriveWebContentsManager::StartLoad() {
         profile_, content::SiteInstance::CreateForURL(profile_, url));
 
   web_contents_.reset(content::WebContents::Create(create_params));
+  WebContentsSource::CreateForWebContentsAndLocation(web_contents_.get(),
+                                                     FROM_HERE);
   web_contents_->SetDelegate(this);
   extensions::ChromeExtensionWebContentsObserver::CreateForWebContents(
       web_contents_.get());