X11: Add TestDesktopScreenX11 to simulate mouse movement in ui tests

ui/views/test/test_desktop_screen_x11.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 "ui/views/test/test_desktop_screen_x11.h"
+
+#include "base/memory/singleton.h"
+
+namespace views {
+namespace test {
+
+TestDesktopScreenX11* TestDesktopScreenX11::GetInstance() {
+  return base::Singleton<TestDesktopScreenX11>::get();
+}
+
+TestDesktopScreenX11::TestDesktopScreenX11() {}
+
+TestDesktopScreenX11::~TestDesktopScreenX11() {}
+
+gfx::Point TestDesktopScreenX11::GetCursorScreenPoint() {
+  return cursor_screen_point_;
+}
+
+TestDesktopScreenX11* GetTestDesktopScreenX11() {
+  static std::unique_ptr<TestDesktopScreenX11> test_screen_instance;
+  if (!test_screen_instance.get())
+    test_screen_instance.reset(new TestDesktopScreenX11());
+  return test_screen_instance.get();
+}
+
+}  // namespace test
+}  // namespace views