Handle touchpad flings with passive event listeners on compositor thread.

content/renderer/input/input_handler_manager_client.h

Index: content/renderer/input/input_handler_manager_client.h
diff --git a/content/renderer/input/input_handler_manager_client.h b/content/renderer/input/input_handler_manager_client.h
index a65ad731cbd3b4c69be40d6d4374cae611ed3379..000abaaafe6db73b9217042ee60fb2260ecc26e2 100644
--- a/content/renderer/input/input_handler_manager_client.h
+++ b/content/renderer/input/input_handler_manager_client.h
@@ -11,6 +11,7 @@
 #include "content/common/content_export.h"
 #include "content/common/input/input_event_ack_state.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
+#include "ui/events/blink/scoped_web_input_event.h"
 #include "ui/gfx/geometry/vector2d_f.h"
 
 namespace ui {
@@ -23,6 +24,7 @@ class InputHandler;
 }
 
 namespace ui {
+class LatencyInfo;
 class SynchronousInputHandlerProxy;
 }
 
@@ -53,6 +55,10 @@ class CONTENT_EXPORT InputHandlerManagerClient {
                              const ui::DidOverscrollParams& params) = 0;
   virtual void DidStartFlinging(int routing_id) = 0;
   virtual void DidStopFlinging(int routing_id) = 0;
+  virtual void DispatchNonBlockingEventToMainThread(
+      int routing_id,
+      ui::ScopedWebInputEvent event,
+      const ui::LatencyInfo& latency_info) = 0;
 
  protected:
   InputHandlerManagerClient() {}