Fix a bunch of IWYU violators that don't include scoped_ptr.h

media/muxers/webm_muxer.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 MEDIA_MUXERS_WEBM_MUXER_H_
 #define MEDIA_MUXERS_WEBM_MUXER_H_
 
 #include <stdint.h>
 
 #include <deque>
 
 #include "base/callback.h"
 #include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/numerics/safe_math.h"
 #include "base/strings/string_piece.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "base/timer/elapsed_timer.h"
 #include "media/base/media_export.h"
 #include "media/base/video_codecs.h"
 #include "third_party/libwebm/source/mkvmuxer.hpp"
 
 namespace gfx {
@@ skipping 117 matching lines @@
     DISALLOW_IMPLICIT_CONSTRUCTORS(EncodedVideoFrame);
   };
   std::deque<scoped_ptr<EncodedVideoFrame>> encoded_frames_queue_;
 
   DISALLOW_COPY_AND_ASSIGN(WebmMuxer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_MUXERS_WEBM_MUXER_H_