Update WindowTree::OnWindowInputEventAck to include handled

ui/views/mus/platform_window_mus.cc

Index: ui/views/mus/platform_window_mus.cc
diff --git a/ui/views/mus/platform_window_mus.cc b/ui/views/mus/platform_window_mus.cc
index 39613901f4d09642d1c4d84dd60c3365d946621c..2a1fc4e3ef4ea5b13f1d143c172bb050f19722cb 100644
--- a/ui/views/mus/platform_window_mus.cc
+++ b/ui/views/mus/platform_window_mus.cc
@@ -223,11 +223,11 @@ void PlatformWindowMus::OnRequestClose(mus::Window* window) {
 void PlatformWindowMus::OnWindowInputEvent(
     mus::Window* view,
     mus::mojom::EventPtr event,
-    scoped_ptr<base::Closure>* ack_callback) {
+    scoped_ptr<base::Callback<void(bool)>>* ack_callback) {
   // It's possible dispatching the event will spin a nested message loop. Ack
   // the callback now, otherwise we appear unresponsive for the life of the
   // nested message loop.
-  (*ack_callback)->Run();
+  (*ack_callback)->Run(true);
   ack_callback->reset();
   scoped_ptr<ui::Event> ui_event(event.To<scoped_ptr<ui::Event>>());
   delegate_->DispatchEvent(ui_event.get());