mash: Preliminary support for widget hit test masks

components/mus/ws/window_tree.cc

Index: components/mus/ws/window_tree.cc
diff --git a/components/mus/ws/window_tree.cc b/components/mus/ws/window_tree.cc
index 0e6a4aa4700321693de6c0282cee1d2873756c3f..979ba5a65f772ad32bd45cd29b6b2347f58beece 100644
--- a/components/mus/ws/window_tree.cc
+++ b/components/mus/ws/window_tree.cc
@@ -1301,6 +1301,17 @@ void WindowTree::SetClientArea(
   window->SetClientArea(insets.To<gfx::Insets>(), additional_client_areas);
 }
 
+void WindowTree::SetHitTestMask(Id transport_window_id, mojo::RectPtr mask) {
+  ServerWindow* window =
+      GetWindowByClientId(ClientWindowId(transport_window_id));
+  if (!window || !access_policy_->CanSetHitTestMask(window)) {
+    DVLOG(1) << "SetHitTestMask failed";
+    return;
+  }
+
+  window->set_hit_test_mask(mask.To<gfx::Rect>());
+}
+
 void WindowTree::Embed(Id transport_window_id,
                        mojom::WindowTreeClientPtr client,
                        const EmbedCallback& callback) {