gfx::Screen: Replace GetWindowUnderCursor() with IsWindowUnderCursor().

ui/gfx/test/test_screen.cc

 // Copyright 2015 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 <vector>
 
 #include "ui/gfx/test/test_screen.h"
 
 namespace gfx {
 namespace test {
 
 TestScreen::TestScreen() {
 }
 
 TestScreen::~TestScreen() {
 }
 
 gfx::Point TestScreen::GetCursorScreenPoint() {
   return gfx::Point();
 }
 
-gfx::NativeWindow TestScreen::GetWindowUnderCursor() {
-  return nullptr;
+bool TestScreen::IsWindowUnderCursor(gfx::NativeWindow window) {
+  return false;
 }
 
 gfx::NativeWindow TestScreen::GetWindowAtScreenPoint(const gfx::Point& point) {
   return nullptr;
 }
 
 int TestScreen::GetNumDisplays() const {
   return 1;
 }
 
@@ skipping 18 matching lines @@
 }
 
 void TestScreen::AddObserver(gfx::DisplayObserver* observer) {
 }
 
 void TestScreen::RemoveObserver(gfx::DisplayObserver* observer) {
 }
 
 }  // namespace test
 }  // namespace gfx