Remove unused include in sequenced_worker_pool.h

content/renderer/media/gpu/rtc_video_encoder.h

 // 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.
 
 #ifndef CONTENT_RENDERER_MEDIA_GPU_RTC_VIDEO_ENCODER_H_
 #define CONTENT_RENDERER_MEDIA_GPU_RTC_VIDEO_ENCODER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "content/common/content_export.h"
 #include "media/base/video_decoder_config.h"
 #include "third_party/webrtc/modules/video_coding/include/video_codec_interface.h"
 #include "ui/gfx/geometry/size.h"
 
+namespace base {
+class SingleThreadTaskRunner;
+}
+
 namespace media {
 class GpuVideoAcceleratorFactories;
 }  // namespace media
 
 namespace content {
 
 // RTCVideoEncoder uses a media::VideoEncodeAccelerator to implement a
 // webrtc::VideoEncoder class for WebRTC.  Internally, VEA methods are
 // trampolined to a private RTCVideoEncoder::Impl instance.  The Impl class runs
 // on the worker thread queried from the |gpu_factories_|, which is presently
@@ skipping 40 matching lines @@
 
   // The RTCVideoEncoder::Impl that does all the work.
   scoped_refptr<Impl> impl_;
 
   DISALLOW_COPY_AND_ASSIGN(RTCVideoEncoder);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_GPU_RTC_VIDEO_ENCODER_H_