Update WindowTree::OnWindowInputEventAck to include handled

content/renderer/input/render_widget_input_handler.h

Index: content/renderer/input/render_widget_input_handler.h
diff --git a/content/renderer/input/render_widget_input_handler.h b/content/renderer/input/render_widget_input_handler.h
index 3be968cb908402d68cbdd98df585cb9203a6e781..a82968bfe3b5ca6c90852250ca7b1b2aa613bcc8 100644
--- a/content/renderer/input/render_widget_input_handler.h
+++ b/content/renderer/input/render_widget_input_handler.h
@@ -34,12 +34,12 @@ class CONTENT_EXPORT RenderWidgetInputHandler {
  public:
   RenderWidgetInputHandler(RenderWidgetInputHandlerDelegate* delegate,
                            RenderWidget* widget);
-  ~RenderWidgetInputHandler();
+  virtual ~RenderWidgetInputHandler();
 
   // Handle input events from the input event provider.
-  void HandleInputEvent(const blink::WebInputEvent& input_event,
-                        const ui::LatencyInfo& latency_info,
-                        InputEventDispatchType dispatch_type);
+  virtual void HandleInputEvent(const blink::WebInputEvent& input_event,
+                                const ui::LatencyInfo& latency_info,
+                                InputEventDispatchType dispatch_type);
 
   // Handle overscroll from Blink.
   void DidOverscrollFromBlink(