mash: Convert OnWindowInputEventAck to use an enum for handled status

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 1c21eadd8683776456d27552805bc09805e793f4..4b72979b40ce92857c8d88346fcdc320a7a2eb10 100644
--- a/ui/views/mus/platform_window_mus.cc
+++ b/ui/views/mus/platform_window_mus.cc
@@ -223,11 +223,12 @@ void PlatformWindowMus::OnRequestClose(mus::Window* window) {
 void PlatformWindowMus::OnWindowInputEvent(
     mus::Window* view,
     const ui::Event& event,
-    std::unique_ptr<base::Callback<void(bool)>>* ack_callback) {
+    std::unique_ptr<base::Callback<void(mus::mojom::EventResult)>>*
+        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(true);
+  (*ack_callback)->Run(mus::mojom::EventResult::HANDLED);
   ack_callback->reset();
   // TODO(moshayedi): Avoid cloning after updating PlatformWindowDelegate to
   // accept constant pointers.