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

services/ui/public/cpp/window_tree_client.h

Index: services/ui/public/cpp/window_tree_client.h
diff --git a/services/ui/public/cpp/window_tree_client.h b/services/ui/public/cpp/window_tree_client.h
index 07b6635c5f0a2d65b7d0b31ad193d341250120a3..adf874e70ed0f6616e3ae82c1cc787de869ca6f6 100644
--- a/services/ui/public/cpp/window_tree_client.h
+++ b/services/ui/public/cpp/window_tree_client.h
@@ -203,6 +203,8 @@ class WindowTreeClient : public mojom::WindowTreeClient,
   void AddObserver(WindowTreeClientObserver* observer);
   void RemoveObserver(WindowTreeClientObserver* observer);
 
+  void SetCanAcceptEvents(Id window_id, bool can_accept_events);
+
 #if !defined(NDEBUG)
   std::string GetDebugWindowHierarchy() const;
   void BuildDebugInfo(const std::string& depth,
@@ -400,6 +402,11 @@ class WindowTreeClient : public mojom::WindowTreeClient,
 
   bool in_destructor_;
 
+  // Whether this window can accept events.
+  // Initialize it to be true since server window will also initialize
+  // can_accept_events_ to be true.
+  bool can_accept_events_ = true;
+
   // A mapping to shared memory that is one 32 bit integer long. The window
   // server uses this to let us synchronously read the cursor location.
   mojo::ScopedSharedBufferMapping cursor_location_mapping_;