Don't use PostTask queueing between compositor and main thread.

content/renderer/input/input_handler_manager.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/input/input_handler_manager.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/location.h"
@@ skipping 171 matching lines @@
   InputHandlerProxy* proxy = it->second->input_handler_proxy();
   DCHECK(proxy->scroll_elasticity_controller());
   proxy->scroll_elasticity_controller()->ObserveGestureEventAndResult(
       gesture_event, scroll_result);
 }
 
 void InputHandlerManager::NotifyInputEventHandledOnMainThread(
     int routing_id,
     blink::WebInputEvent::Type type,
     InputEventAckState ack_result) {
-  task_runner_->PostTask(
-      FROM_HERE,
-      base::Bind(
-          &InputHandlerManager::NotifyInputEventHandledOnCompositorThread,
-          base::Unretained(this), routing_id, type, ack_result));
-}
-
-void InputHandlerManager::NotifyInputEventHandledOnCompositorThread(
-    int routing_id,
-    blink::WebInputEvent::Type handled_type,
-    InputEventAckState ack_result) {
-  DCHECK(task_runner_->BelongsToCurrentThread());
-  auto it = input_handlers_.find(routing_id);
-  if (it == input_handlers_.end())
-    return;
-
-  client_->NotifyInputEventHandled(routing_id, handled_type, ack_result);
+  client_->NotifyInputEventHandled(routing_id, type, ack_result);
 }
 
 InputEventAckState InputHandlerManager::HandleInputEvent(
     int routing_id,
     const WebInputEvent* input_event,
     ui::LatencyInfo* latency_info) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   TRACE_EVENT1("input,benchmark", "InputHandlerManager::HandleInputEvent",
                  "type", WebInputEventTraits::GetName(input_event->type));
 
@@ skipping 38 matching lines @@
 
 void InputHandlerManager::DidStopFlinging(int routing_id) {
   client_->DidStopFlinging(routing_id);
 }
 
 void InputHandlerManager::DidAnimateForInput() {
   renderer_scheduler_->DidAnimateForInputOnCompositorThread();
 }
 
 }  // namespace content