Handle touchpad flings with passive event listeners on compositor thread.

content/renderer/input/input_event_filter.h

Index: content/renderer/input/input_event_filter.h
diff --git a/content/renderer/input/input_event_filter.h b/content/renderer/input/input_event_filter.h
index e45e3a99e2f9e0a04cf6662fc90940707e11032d..727a5cb8af944cbf5c10001efe6f1cc304652a63 100644
--- a/content/renderer/input/input_event_filter.h
+++ b/content/renderer/input/input_event_filter.h
@@ -69,6 +69,10 @@ class CONTENT_EXPORT InputEventFilter : public InputHandlerManagerClient,
                      const ui::DidOverscrollParams& params) override;
   void DidStartFlinging(int routing_id) override;
   void DidStopFlinging(int routing_id) override;
+  void DispatchNonBlockingEventToMainThread(
+      int routing_id,
+      ui::ScopedWebInputEvent event) override;
+
   void NotifyInputEventHandled(int routing_id,
                                blink::WebInputEvent::Type type,
                                InputEventAckState ack_result) override;