Add support for encrypted WebM files as defined in the RFC.

media/webm/webm_stream_parser.cc

 // Copyright (c) 2012 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 "media/webm/webm_stream_parser.h"
 
 #include "base/callback.h"
 #include "base/logging.h"
 #include "media/ffmpeg/ffmpeg_common.h"
 #include "media/filters/ffmpeg_glue.h"
@@ skipping 334 matching lines @@
   if (!config_cb_.Run(config_helper.audio_config(),
                       config_helper.video_config())) {
     DVLOG(1) << "New config data isn't allowed.";
     return -1;
   }
 
   // TODO(xhwang): Support decryption of audio (see http://crbug.com/123421).
   if (tracks_parser.video_encryption_key_id()) {
     int key_id_size = tracks_parser.video_encryption_key_id_size();
     CHECK_GT(key_id_size, 0);
+    CHECK_LT(key_id_size, 2048);
     scoped_array<uint8> key_id(new uint8[key_id_size]);
     memcpy(key_id.get(), tracks_parser.video_encryption_key_id(), key_id_size);
     need_key_cb_.Run(key_id.Pass(), key_id_size);
   }
 
   cluster_parser_.reset(new WebMClusterParser(
       info_parser.timecode_scale(),
       tracks_parser.audio_track_num(),
       tracks_parser.video_track_num(),
       tracks_parser.video_encryption_key_id(),
@@ skipping 54 matching lines @@
   if (!audio_buffers.empty() && !audio_cb_.Run(audio_buffers))
     return -1;
 
   if (!video_buffers.empty() && !video_cb_.Run(video_buffers))
     return -1;
 
   return bytes_parsed;
 }
 
 }  // namespace media