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

ui/ozone/platform/wayland/wayland_display_unittest.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 <wayland-server-core.h>
 #include <xdg-shell-unstable-v5-server-protocol.h>
 
+#include "base/run_loop.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/ozone/platform/wayland/fake_server.h"
 #include "ui/ozone/platform/wayland/wayland_display.h"
 
 namespace ui {
 
 TEST(WaylandDisplayTest, UseUnstableVersion) {
+  base::MessageLoopForUI message_loop;
   wl::FakeServer server;
   EXPECT_CALL(*server.xdg_shell(),
               UseUnstableVersion(XDG_SHELL_VERSION_CURRENT));
   ASSERT_TRUE(server.Start());
   WaylandDisplay display;
   ASSERT_TRUE(display.Initialize());
-  wl_display_roundtrip(display.display());
+  display.StartProcessingEvents();
+
+  base::RunLoop().RunUntilIdle();
+  server.Pause();
 }
 
 TEST(WaylandDisplayTest, Ping) {
+  base::MessageLoopForUI message_loop;
   wl::FakeServer server;
   ASSERT_TRUE(server.Start());
   WaylandDisplay display;
   ASSERT_TRUE(display.Initialize());
-  wl_display_roundtrip(display.display());
+  display.StartProcessingEvents();
 
+  base::RunLoop().RunUntilIdle();
   server.Pause();
 
   xdg_shell_send_ping(server.xdg_shell()->resource(), 1234);
   EXPECT_CALL(*server.xdg_shell(), Pong(1234));
-  server.Flush();
 
   server.Resume();
-
-  wl_display_roundtrip(display.display());
+  base::RunLoop().RunUntilIdle();
+  server.Pause();
 }
 
 }  // namespace ui