Remove unused include in sequenced_worker_pool.h

remoting/protocol/webrtc_dummy_video_encoder.h

 // Copyright 2016 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.
 
 #ifndef REMOTING_PROTOCOL_WEBRTC_DUMMY_VIDEO_ENCODER_H_
 #define REMOTING_PROTOCOL_WEBRTC_DUMMY_VIDEO_ENCODER_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
 #include "base/synchronization/lock.h"
 #include "remoting/codec/webrtc_video_encoder.h"
 #include "third_party/webrtc/media/engine/webrtcvideoencoderfactory.h"
 #include "third_party/webrtc/modules/video_coding/include/video_codec_interface.h"
 
 namespace remoting {
 namespace protocol {
 
 class VideoChannelStateObserver;
 
@@ skipping 77 matching lines @@
   // Protects |video_channel_state_observer_| and |encoders_|.
   base::Lock lock_;
   base::WeakPtr<VideoChannelStateObserver> video_channel_state_observer_;
   std::vector<std::unique_ptr<WebrtcDummyVideoEncoder>> encoders_;
 };
 
 }  // namespace protocol
 }  // namespace remoting
 
 #endif  // REMOTING_PROTOCOL_WEBRTC_DUMMY_VIDEO_ENCODER_H_