mash: Preliminary support for widget hit test masks

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 4baf37b2b1a5cde0420afc84ba6192581f8583c9..05db1876d7fa2ac18ea586d0a8da12837f42281a 100644
--- a/components/mus/ws/server_window.h
+++ b/components/mus/ws/server_window.h
@@ -82,6 +82,10 @@ class ServerWindow {
   void SetClientArea(const gfx::Insets& insets,
                      const std::vector<gfx::Rect>& additional_client_areas);
 
+  bool HasHitTestMask() const { return !hit_test_mask_.IsEmpty(); }
+  const gfx::Rect& hit_test_mask() const { return hit_test_mask_; }
+  void set_hit_test_mask(const gfx::Rect& mask) { hit_test_mask_ = mask; }
+
   int32_t cursor() const { return static_cast<int32_t>(cursor_id_); }
   int32_t non_client_cursor() const {
     return static_cast<int32_t>(non_client_cursor_id_);
@@ -230,6 +234,10 @@ class ServerWindow {
   // amount.
   gfx::Insets extended_hit_test_region_;
 
+  // Mouse events outside the hit test mask don't hit the window. If empty
+  // there is no mask.
+  gfx::Rect hit_test_mask_;

[sky, 2016/05/19 18:13:17]

I think this should be a pointer, so that clients can specify no hit test mask
(null), empty, meaning there is no valid region of the window, or a mask.

[James Cook, 2016/05/19 21:47:46]

Done.

+
   base::ObserverList<ServerWindowObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(ServerWindow);