arc: Use the new InstanceHolder for unittests

components/arc/test/fake_notifications_instance.h

 // 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.
 
 #ifndef COMPONENTS_ARC_TEST_FAKE_NOTIFICATIONS_INSTANCE_H_
 #define COMPONENTS_ARC_TEST_FAKE_NOTIFICATIONS_INSTANCE_H_
 
 #include "components/arc/common/notifications.mojom.h"
 #include "components/arc/test/fake_arc_bridge_instance.h"
 
 namespace arc {
 
 class FakeNotificationsInstance : public mojom::NotificationsInstance {
  public:
-  FakeNotificationsInstance(
-      mojo::InterfaceRequest<mojom::NotificationsInstance> request);
+  FakeNotificationsInstance();
   ~FakeNotificationsInstance() override;
 
   void Init(mojom::NotificationsHostPtr host_ptr) override;
 
   void SendNotificationEventToAndroid(
       const mojo::String& key,
       mojom::ArcNotificationEvent event) override;
 
   const std::vector<std::pair<mojo::String, mojom::ArcNotificationEvent>>&
   events() const;
 
-  void WaitForIncomingMethodCall();
-
  private:
   std::vector<std::pair<mojo::String, mojom::ArcNotificationEvent>> events_;
 
-  mojo::Binding<mojom::NotificationsInstance> binding_;
-
   DISALLOW_COPY_AND_ASSIGN(FakeNotificationsInstance);
 };
 
 }  // namespace arc
 
 #endif  // COMPONENTS_ARC_TEST_FAKE_NOTIFICATIONS_INSTANCE_H_