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

ui/gfx/screen_mac.mm

 // 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/gfx/screen.h"
 
 #import <ApplicationServices/ApplicationServices.h>
 #import <Cocoa/Cocoa.h>
 #include <stdint.h>
 
@@ skipping 77 matching lines @@
   ~ScreenMac() override {
     CGDisplayRemoveReconfigurationCallback(
         ScreenMac::DisplayReconfigurationCallBack, this);
   }
 
   gfx::Point GetCursorScreenPoint() override {
     // Flip coordinates to gfx (0,0 in top-left corner) using primary screen.
     return gfx::ScreenPointFromNSPoint([NSEvent mouseLocation]);
   }
 
-  gfx::NativeWindow GetWindowUnderCursor() override {
+  bool IsWindowUnderCursor(gfx::NativeWindow window) override {
     NOTIMPLEMENTED();
-    return gfx::NativeWindow();
+    return false;
   }
 
   gfx::NativeWindow GetWindowAtScreenPoint(const gfx::Point& point) override {
     NOTIMPLEMENTED();
     return gfx::NativeWindow();
   }
 
   int GetNumDisplays() const override { return GetAllDisplays().size(); }
 
   std::vector<gfx::Display> GetAllDisplays() const override {
@@ skipping 149 matching lines @@
 
 namespace gfx {
 
 #if !defined(USE_AURA)
 Screen* CreateNativeScreen() {
   return new ScreenMac;
 }
 #endif
 
 }