Fix a crash due to UserScriptListener unregistering notifications on the wrong

chrome/browser/extensions/user_script_listener.cc

Index: chrome/browser/extensions/user_script_listener.cc
diff --git a/chrome/browser/extensions/user_script_listener.cc b/chrome/browser/extensions/user_script_listener.cc
index aec615cb74fdee7d89b7ed2350a68c5f6dbb1bef..aba4a6b89477f8f5a3a64bbd1b0ac4f2552142a7 100644
--- a/chrome/browser/extensions/user_script_listener.cc
+++ b/chrome/browser/extensions/user_script_listener.cc
@@ -16,6 +16,7 @@
 UserScriptListener::UserScriptListener(ResourceQueue* resource_queue)
     : resource_queue_(resource_queue),
       user_scripts_ready_(false) {
+  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
   DCHECK(resource_queue_);
 
   registrar_.Add(this, NotificationType::EXTENSION_LOADED,
@@ -26,6 +27,11 @@ UserScriptListener::UserScriptListener(ResourceQueue* resource_queue)
                  NotificationService::AllSources());
 }
 
+void UserScriptListener::ShutdownMainThread() {
+  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
+  registrar_.RemoveAll();
+}
+
 bool UserScriptListener::ShouldDelayRequest(
     URLRequest* request,
     const ResourceDispatcherHostRequestInfo& request_info,