Handle touchpad flings with passive event listeners on compositor thread.

content/renderer/mus/compositor_mus_connection_unittest.cc

Index: content/renderer/mus/compositor_mus_connection_unittest.cc
diff --git a/content/renderer/mus/compositor_mus_connection_unittest.cc b/content/renderer/mus/compositor_mus_connection_unittest.cc
index e6d813637405f7a982382872c6f3b7d27c7c6548..7d3ecd046a3ecf3e1c156d10de700d9269d8e15c 100644
--- a/content/renderer/mus/compositor_mus_connection_unittest.cc
+++ b/content/renderer/mus/compositor_mus_connection_unittest.cc
@@ -129,6 +129,11 @@ class TestInputHandlerManagerClient
                      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,
+      const ui::LatencyInfo& latency_info) override {}
+
   void NotifyInputEventHandled(
       int routing_id,
       blink::WebInputEvent::Type type,