Check WindowTreeClient for empty inflight queue upon teardown

components/mus/public/cpp/tests/window_tree_client_private.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_MUS_PUBLIC_CPP_TESTS_WINDOW_TREE_CLIENT_PRIVATE_H_
 #define COMPONENTS_MUS_PUBLIC_CPP_TESTS_WINDOW_TREE_CLIENT_PRIVATE_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 20 matching lines @@
   ~WindowTreeClientPrivate();
 
   uint32_t event_observer_id();
 
   // Calls OnEmbed() on the WindowTreeClient.
   void OnEmbed(mojom::WindowTree* window_tree);
 
   // Pretends that |event| has been received from the window server.
   void CallOnWindowInputEvent(Window* window, std::unique_ptr<ui::Event> event);
 
+  // For tests which do not connect to the Mus Window Server, the stubbed
+  // connection does not respond to messages. This clears the in flight queue of
+  // requests so that tear down can occur.
+  void ClearInFlightQueue();
+
+  // For tests which do connect to the Mus Window Server. This runs until the
+  // |tree_client_impl_| has received acknowledgements for each message sent to
+  // the server.
+  void WaitForInFlightQueue();
+
  private:
    WindowTreeClient* tree_client_impl_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeClientPrivate);
 };
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_PUBLIC_CPP_TESTS_WINDOW_TREE_CLIENT_PRIVATE_H_