arc-bridge: Make ArcAppModelBuilderTest more reliable

components/arc/test/fake_app_instance.h

 // Copyright 2015 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_APP_INSTANCE_H_
 #define COMPONENTS_ARC_TEST_FAKE_APP_INSTANCE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 67 matching lines @@
   int refresh_app_list_count() const { return refresh_app_list_count_; }
 
   const ScopedVector<Request>& launch_requests() const {
     return launch_requests_;
   }
 
   const ScopedVector<IconRequest>& icon_requests() const {
     return icon_requests_;
   }
 
+  // This method can be called on tests when a method is intended to
+  // be called across a Mojo proxy.
+  void WaitForIncomingMethodCall();
+
  private:
   // Mojo endpoints.
   mojo::Binding<AppInstance> binding_;
   AppHost* app_host_;
   // Number of RefreshAppList calls.
   int refresh_app_list_count_ = 0;
   // Keeps information about launch requests.
   ScopedVector<Request> launch_requests_;
   // Keeps information about icon load requests.
   ScopedVector<IconRequest> icon_requests_;
 };
 
 }  // namespace arc
 
 #endif  // COMPONENTS_ARC_TEST_FAKE_APP_INSTANCE_H_