mash: Convert OnWindowInputEventAck to use an enum for handled status

components/mus/public/cpp/lib/window_tree_client_impl.cc

Index: components/mus/public/cpp/lib/window_tree_client_impl.cc
diff --git a/components/mus/public/cpp/lib/window_tree_client_impl.cc b/components/mus/public/cpp/lib/window_tree_client_impl.cc
index 9b199da20cc8d1fb99f9ed7d151ce3152a046265..23cc50de852f8f286bb2f203dd2c3bc5f2442b9f 100644
--- a/components/mus/public/cpp/lib/window_tree_client_impl.cc
+++ b/components/mus/public/cpp/lib/window_tree_client_impl.cc
@@ -868,12 +868,12 @@ void WindowTreeClientImpl::OnWindowInputEvent(uint32_t event_id,
                                               mojom::EventPtr event) {
   Window* window = GetWindowByServerId(window_id);
   if (!window || !window->input_event_handler_) {
-    tree_->OnWindowInputEventAck(event_id, false);
+    tree_->OnWindowInputEventAck(event_id, mojom::EventResult::UNHANDLED);
     return;
   }
 
-  scoped_ptr<base::Callback<void(bool)>> ack_callback(
-      new base::Callback<void(bool)>(
+  scoped_ptr<base::Callback<void(mojom::EventResult)>> ack_callback(
+      new base::Callback<void(mojom::EventResult)>(
           base::Bind(&mojom::WindowTree::OnWindowInputEventAck,
                      base::Unretained(tree_), event_id)));
   window->input_event_handler_->OnWindowInputEvent(
@@ -882,7 +882,7 @@ void WindowTreeClientImpl::OnWindowInputEvent(uint32_t event_id,
   // The handler did not take ownership of the callback, so we send the ack,
   // marking the event as not consumed.
   if (ack_callback)
-    ack_callback->Run(false);
+    ack_callback->Run(mojom::EventResult::UNHANDLED);
 }
 
 void WindowTreeClientImpl::OnWindowFocused(Id focused_window_id) {