Remove unused include in sequenced_worker_pool.h

content/renderer/media/html_video_element_capturer_source.h

 // Copyright 2015 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_HTML_VIDEO_ELEMENT_CAPTURER_SOURCE_H_
 #define CONTENT_RENDERER_MEDIA_HTML_VIDEO_ELEMENT_CAPTURER_SOURCE_H_
 
 #include "base/callback.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_frame_pool.h"
 #include "media/base/video_types.h"
 #include "media/capture/video_capturer_source.h"
 #include "third_party/WebKit/public/platform/WebSize.h"
 #include "third_party/skia/include/core/SkRefCnt.h"
 
+namespace base{
+class SingleThreadTaskRunner;
+}
+
 namespace blink {
 class WebMediaPlayer;
 }  // namespace blink
 
 class SkSurface;
 
 namespace content {
 
 // This class is a VideoCapturerSource taking video snapshots of the ctor-passed
 // blink::WebMediaPlayer on Render Main thread. The captured data is converted
@@ skipping 46 matching lines @@
 
   // Used on main render thread to schedule future capture events.
   base::WeakPtrFactory<HtmlVideoElementCapturerSource> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HtmlVideoElementCapturerSource);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_HTML_VIDEO_ELEMENT_CAPTURER_SOURCE_H_