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

chromecast/graphics/cast_screen.cc

Index: chromecast/graphics/cast_screen.cc
diff --git a/chromecast/graphics/cast_screen.cc b/chromecast/graphics/cast_screen.cc
index db4079fa533deb1254eca5d805a12ec1a8fd5816..b88d75a61c2a643d14b0663b696d2454102861a2 100644
--- a/chromecast/graphics/cast_screen.cc
+++ b/chromecast/graphics/cast_screen.cc
@@ -48,9 +48,9 @@ gfx::Point CastScreen::GetCursorScreenPoint() {
   return aura::Env::GetInstance()->last_mouse_location();
 }
 
-gfx::NativeWindow CastScreen::GetWindowUnderCursor() {
+bool CastScreen::IsWindowUnderCursor(gfx::NativeWindow window) {
   NOTIMPLEMENTED();
-  return gfx::NativeWindow(nullptr);
+  return false;
 }
 
 gfx::NativeWindow CastScreen::GetWindowAtScreenPoint(const gfx::Point& point) {