ozone/platform/wayland: Use more realistic event processing and request flushing in tests

ui/ozone/platform/wayland/wayland_test.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 UI_OZONE_PLATFORM_WAYLAND_WAYLAND_TEST_H_
 #define UI_OZONE_PLATFORM_WAYLAND_WAYLAND_TEST_H_
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/ozone/platform/wayland/fake_server.h"
 #include "ui/ozone/platform/wayland/mock_platform_window_delegate.h"
@@ skipping 10 matching lines @@
   ~WaylandTest() override;
 
   void SetUp() override;
   void TearDown() override;
 
   void Sync();
 
  private:
   bool initialized = false;
   wl::FakeServer server;
+  base::MessageLoopForUI message_loop;
 
  protected:
   wl::MockSurface* surface;
 
   WaylandDisplay display;
   MockPlatformWindowDelegate delegate;
   WaylandWindow window;
   gfx::AcceleratedWidget widget = gfx::kNullAcceleratedWidget;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(WaylandTest);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_WAYLAND_WAYLAND_TEST_H_