X11: Add TestDesktopScreenX11 to simulate mouse movement in ui tests

ui/views/widget/desktop_aura/desktop_screen_x11.cc

 // Copyright (c) 2012 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/widget/desktop_aura/desktop_screen_x11.h"
 
 #include <X11/extensions/Xrandr.h>
 #include <X11/Xlib.h>
 
 // It clashes with out RootWindow.
@@ skipping 387 matching lines @@
 }
 
 void DesktopScreenX11::SetDisplaysInternal(
     const std::vector<display::Display>& displays) {
   displays_ = displays;
   gfx::SetFontRenderParamsDeviceScaleFactor(
       GetPrimaryDisplay().device_scale_factor());
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+// TestDesktopScreenX11, public:
+
+TestDesktopScreenX11::TestDesktopScreenX11() {}
+
+TestDesktopScreenX11::~TestDesktopScreenX11() {}
+
+gfx::Point TestDesktopScreenX11::GetCursorScreenPoint() {
+  return cursor_screen_point_;
+}
+
+void TestDesktopScreenX11::SetCursorScreenPoint(const gfx::Point& point) {
+  cursor_screen_point_ = point;
+}
+
+////////////////////////////////////////////////////////////////////////////////
 
 display::Screen* CreateDesktopScreen() {
   return new DesktopScreenX11;
 }
 
+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 views