mus: Implement ScreenMus::GetCursorScreenPoint().

components/mus/ws/window_tree.h

Index: components/mus/ws/window_tree.h
diff --git a/components/mus/ws/window_tree.h b/components/mus/ws/window_tree.h
index 43639d257231008775cd636ab94bfe3ca22a45b0..06ca59fd96e296fe153140b3f7f550b8bbd5984e 100644
--- a/components/mus/ws/window_tree.h
+++ b/components/mus/ws/window_tree.h
@@ -246,6 +246,9 @@ class WindowTree : public mojom::WindowTree,
   Display* GetDisplayForWindowManager();
   WindowManagerState* GetWindowManagerStateForWindowManager();
 
+  // Gets the current |user_id_|'s window manager state.
+  WindowManagerState* GetWindowManagerStateForUser();
+
   bool ShouldRouteToWindowManager(const ServerWindow* window) const;
 
   ClientWindowId ClientWindowIdForWindow(const ServerWindow* window) const;
@@ -384,6 +387,8 @@ class WindowTree : public mojom::WindowTree,
   void GetWindowManagerClient(
       mojo::AssociatedInterfaceRequest<mojom::WindowManagerClient> internal)
       override;
+  void GetCursorLocationMemory(const GetCursorLocationMemoryCallback& callback)
+      override;
 
   // mojom::WindowManagerClient:
   void AddAccelerator(uint32_t id,