Teach main thread event queue about closures.

content/renderer/input/input_event_filter.cc

Index: content/renderer/input/input_event_filter.cc
diff --git a/content/renderer/input/input_event_filter.cc b/content/renderer/input/input_event_filter.cc
index 1cb4efe7ea2e119301d96a7ecc5b513f668d2f05..32259cf4b78cf68724f169db109d4d1931087893 100644
--- a/content/renderer/input/input_event_filter.cc
+++ b/content/renderer/input/input_event_filter.cc
@@ -95,6 +95,15 @@ void InputEventFilter::DidStopFlinging(int routing_id) {
   SendMessage(base::MakeUnique<InputHostMsg_DidStopFlinging>(routing_id));
 }
 
+void InputEventFilter::QueueClosureForMainThreadEventQueue(
+    int routing_id,
+    const base::Closure& closure) {
+  DCHECK(target_task_runner_->BelongsToCurrentThread());
+  RouteQueueMap::iterator iter = route_queues_.find(routing_id);
+  if (iter != route_queues_.end())
+    iter->second->QueueClosure(closure);
+}
+
 void InputEventFilter::DispatchNonBlockingEventToMainThread(
     int routing_id,
     ui::WebScopedInputEvent event,
@@ -198,18 +207,17 @@ void InputEventFilter::ForwardToHandler(const IPC::Message& message,
   TRACE_EVENT1("input", "InputEventFilter::ForwardToHandler",
                "message_type", GetInputMessageTypeName(message));
 
+  int routing_id = message.routing_id();
   if (message.type() != InputMsg_HandleInputEvent::ID) {
     TRACE_EVENT_INSTANT0(
         "input",
         "InputEventFilter::ForwardToHandler::ForwardToMainListener",
         TRACE_EVENT_SCOPE_THREAD);
-    CHECK(main_task_runner_->PostTask(FROM_HERE,
-                                      base::Bind(main_listener_, message)))
-        << "PostTask failed";
+    input_handler_manager_->QueueClosureForMainThreadEventQueue(
+        routing_id, base::Bind(main_listener_, message));
     return;
   }
 
-  int routing_id = message.routing_id();
   InputMsg_HandleInputEvent::Param params;
   if (!InputMsg_HandleInputEvent::Read(&message, &params))
     return;