mus: Disregard windows that explicitly set can_accept_events to be false when sending events.

services/ui/public/interfaces/window_tree.mojom

Index: services/ui/public/interfaces/window_tree.mojom
diff --git a/services/ui/public/interfaces/window_tree.mojom b/services/ui/public/interfaces/window_tree.mojom
index a15f7bf5c7117e6b21cc6037a3bb34d943b92fab..e6dc01191e3180a6fa4dc4ce5860a51b26464ff4 100644
--- a/services/ui/public/interfaces/window_tree.mojom
+++ b/services/ui/public/interfaces/window_tree.mojom
@@ -223,6 +223,9 @@ interface WindowTree {
   // Otherwise the existing state is used.
   SetImeVisibility(uint32 window_id, bool visible, mojo.TextInputState? state);
 
+  // Set whether to accept events for the given window.

[sky, 2016/07/08 20:35:00]

whether the specified window can accept events.

[riajiang, 2016/07/11 15:48:38]

Done.

+  SetAcceptEvents(uint32 window_id, bool accept_events);
+
   // See documentation for WindowTreeClient::OnWindowInputEvent().
   OnWindowInputEventAck(uint32 event_id, EventResult result);