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..f276ad831a15eab4d987fbd50d1415b67d3bd9f3 100644
--- a/components/mus/ws/window_tree.cc
+++ b/components/mus/ws/window_tree.cc
@@ -1301,6 +1301,20 @@ void WindowTree::SetClientArea(
   window->SetClientArea(insets.To<gfx::Insets>(), additional_client_areas);
 }
 
+void WindowTree::SetHitTestMask(Id transport_window_id, mojo::RectPtr mask) {

[dcheng, 2016/05/20 17:44:19]

Once we have a StructTraits for mojo::RectPtr -> gfx::Rect and remove the
TypeConverter, how will we support the 'nullable rect' case? Will the null
mojo::Rect be translated to the empty gfx::Rect?

[James Cook, 2016/05/20 17:59:48]

I just talked to rockot@. Apparently there's a nullability concept for
StructTraits in the pipeline, so optional mojo.Rects will become either a
base::Optional<> or a unique_ptr<>. We'll need to use something like that here,
since being able to pass a non-null empty rect is desirable in this case.

+  ServerWindow* window =
+      GetWindowByClientId(ClientWindowId(transport_window_id));
+  if (!window || !access_policy_->CanSetHitTestMask(window)) {
+    DVLOG(1) << "SetHitTestMask failed";
+    return;
+  }
+
+  if (mask)
+    window->SetHitTestMask(mask.To<gfx::Rect>());
+  else
+    window->ClearHitTestMask();
+}
+
 void WindowTree::Embed(Id transport_window_id,
                        mojom::WindowTreeClientPtr client,
                        const EmbedCallback& callback) {