mus: Implement ScreenMus::GetCursorScreenPoint().

ui/views/mus/window_manager_connection.cc

Index: ui/views/mus/window_manager_connection.cc
diff --git a/ui/views/mus/window_manager_connection.cc b/ui/views/mus/window_manager_connection.cc
index cfa0a2b2322f11e0a66845b681384155f7232661..a31866b1ce0aaa8b4e48db2b3fb5fd86114d477c 100644
--- a/ui/views/mus/window_manager_connection.cc
+++ b/ui/views/mus/window_manager_connection.cc
@@ -83,6 +83,7 @@ WindowManagerConnection::WindowManagerConnection(
       window_tree_connection_(nullptr) {
   window_tree_connection_.reset(
       mus::WindowTreeConnection::Create(this, connector_));
+  window_tree_connection_->InitializeCursorLocation();
 
   screen_.reset(new ScreenMus(this));
   screen_->Init(connector);
@@ -116,4 +117,8 @@ void WindowManagerConnection::OnWindowManagerFrameValuesChanged() {
     NativeWidgetMus::NotifyFrameChanged(window_tree_connection_.get());
 }
 
+gfx::Point WindowManagerConnection::GetCursorScreenPoint() {
+  return window_tree_connection_->GetCursorScreenPoint();
+}
+
 }  // namespace views