mash: Convert OnWindowInputEventAck to use an enum for handled status

components/mus/public/cpp/input_event_handler.h

Index: components/mus/public/cpp/input_event_handler.h
diff --git a/components/mus/public/cpp/input_event_handler.h b/components/mus/public/cpp/input_event_handler.h
index e40e60e31ee969e3f88f25f7a58755ff91562197..d21354b2d732a937e29f32d0d88bf7467290d4e6 100644
--- a/components/mus/public/cpp/input_event_handler.h
+++ b/components/mus/public/cpp/input_event_handler.h
@@ -16,17 +16,21 @@ namespace mus {
 
 class Window;
 
+namespace mojom {
+enum class EventResult;
+}
+
 // Responsible for processing input events for mus::Window.
 class InputEventHandler {
  public:
   // The event handler can asynchronously ack the event by taking ownership of
-  // the |ack_callback|. The callback takes a bool representing whether the
+  // the |ack_callback|. The callback takes an EventResult indicating if the
   // handler has consumed the event. If the handler does not take ownership of
   // the callback, then WindowTreeClientImpl will ack the event as not consumed.
   virtual void OnWindowInputEvent(
       Window* target,
       const ui::Event& event,
-      scoped_ptr<base::Callback<void(bool)>>* ack_callback) = 0;
+      scoped_ptr<base::Callback<void(mojom::EventResult)>>* ack_callback) = 0;
 
  protected:
   virtual ~InputEventHandler() {}