Handle touchpad flings with passive event listeners on compositor thread.

content/renderer/input/input_handler_manager.h

Index: content/renderer/input/input_handler_manager.h
diff --git a/content/renderer/input/input_handler_manager.h b/content/renderer/input/input_handler_manager.h
index c5ce6c34e1fb0252508aba20b4adfed1cc51c8c7..fd3cd081651af45f7ea077303e7ce6165a908498 100644
--- a/content/renderer/input/input_handler_manager.h
+++ b/content/renderer/input/input_handler_manager.h
@@ -104,6 +104,10 @@ class CONTENT_EXPORT InputHandlerManager {
   // Called from the compositor's thread.
   void NeedsMainFrame(int routing_id);
 
+  // Called from the compositor's thread.
+  void DispatchNonBlockingEventToMainThread(int routing_id,
+                                            ui::ScopedWebInputEvent event);
+
  private:
   // Called from the compositor's thread.
   void AddInputHandlerOnCompositorThread(