Handle touchpad flings with passive event listeners on compositor thread.

content/renderer/input/input_handler_manager.cc

Index: content/renderer/input/input_handler_manager.cc
diff --git a/content/renderer/input/input_handler_manager.cc b/content/renderer/input/input_handler_manager.cc
index e416c97fc909f3a3caa1dc9d0234b504fdcca5b4..d9851a55ba711a56bb674ccb10c48d0be8fd109a 100644
--- a/content/renderer/input/input_handler_manager.cc
+++ b/content/renderer/input/input_handler_manager.cc
@@ -276,4 +276,11 @@ void InputHandlerManager::NeedsMainFrame(int routing_id) {
   it->second->NeedsMainFrame();
 }
 
+void InputHandlerManager::DispatchNonBlockingEventToMainThread(
+    int routing_id,
+    ui::ScopedWebInputEvent event) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  client_->DispatchNonBlockingEventToMainThread(routing_id, std::move(event));
+}
+
 }  // namespace content