mus: Let clients set the cursor of their window.

components/mus/ws/server_window.h

Index: components/mus/ws/server_window.h
diff --git a/components/mus/ws/server_window.h b/components/mus/ws/server_window.h
index 7cadc08faf15489c15edee50e1f038f3d024b9b3..66519bb001a9d9a29dbebbb7cd1409b15435b579 100644
--- a/components/mus/ws/server_window.h
+++ b/components/mus/ws/server_window.h
@@ -74,6 +74,8 @@ class ServerWindow {
   const gfx::Insets& client_area() const { return client_area_; }
   void SetClientArea(const gfx::Insets& insets);
 
+  int32_t cursor() const { return cursor_id_; }
+
   const ServerWindow* parent() const { return parent_; }
   ServerWindow* parent() { return parent_; }
 
@@ -111,6 +113,8 @@ class ServerWindow {
   float opacity() const { return opacity_; }
   void SetOpacity(float value);
 
+  void SetPredefinedCursor(mus::mojom::Cursor cursor_id);
+
   const gfx::Transform& transform() const { return transform_; }
   void SetTransform(const gfx::Transform& transform);
 
@@ -191,6 +195,7 @@ class ServerWindow {
   gfx::Rect bounds_;
   gfx::Insets client_area_;
   scoped_ptr<ServerWindowSurfaceManager> surface_manager_;
+  mojom::Cursor cursor_id_;
   float opacity_;
   bool can_focus_;
   gfx::Transform transform_;