Revert of Switch WindowedNotificationObserver to use base::RunLoop.

extensions/test/extension_test_notification_observer.cc

 // Copyright 2016 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/test/extension_test_notification_observer.h"
 
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/notification_service.h"
@@ skipping 123 matching lines @@
     int type,
     const content::NotificationSource& source) {
   CHECK(!observer_);
   observer_.reset(new content::WindowedNotificationObserver(type, source));
   registrar_.Add(this, type, source);
 }
 
 void ExtensionTestNotificationObserver::Wait() {
   observer_->Wait();
 
-  // TODO(https://crbug.com/695073): Find out why tests fail without it.
-  content::RunAllPendingInMessageLoop();
-
   registrar_.RemoveAll();
   observer_.reset();
 }
 
 void ExtensionTestNotificationObserver::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
   switch (type) {
     case NOTIFICATION_EXTENSION_LOADED_DEPRECATED:
@@ skipping 26 matching lines @@
   }
 }
 
 void ExtensionTestNotificationObserver::WaitForCondition(
     const ConditionCallback& condition,
     NotificationSet* notification_set) {
   if (condition.Run())
     return;
   condition_ = condition;
 
-  base::RunLoop run_loop;
-  quit_closure_ = run_loop.QuitClosure();
+  scoped_refptr<content::MessageLoopRunner> runner(
+      new content::MessageLoopRunner);
+  quit_closure_ = runner->QuitClosure();
 
   std::unique_ptr<base::CallbackList<void()>::Subscription> subscription;
   if (notification_set) {
     subscription = notification_set->callback_list().Add(base::Bind(
         &ExtensionTestNotificationObserver::MaybeQuit, base::Unretained(this)));
   }
-  run_loop.Run();
+  runner->Run();
 
   condition_.Reset();
   quit_closure_.Reset();
 }
 
 void ExtensionTestNotificationObserver::MaybeQuit() {
   if (condition_.Run())
     quit_closure_.Run();
 }
 
 }  // namespace extensions