Add Common Encryption support to BMFF, including subsample decryption.

media/mp4/box_definitions.h

 // 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.
 
 #ifndef MEDIA_MP4_BOX_DEFINITIONS_H_
 #define MEDIA_MP4_BOX_DEFINITIONS_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 199 matching lines @@
 
   TrackType type;
   std::vector<VideoSampleEntry> video_entries;
   std::vector<AudioSampleEntry> audio_entries;
 };
 
 struct MEDIA_EXPORT SampleTable : Box {
   DECLARE_BOX_METHODS(SampleTable);
 
   // Media Source specific: we ignore many of the sub-boxes in this box,
-  // including some that are required to be present in the BMFF spec.
+  // including some that are required to be present in the BMFF spec. This
+  // includes the 'stts', 'stsc', and 'stco' boxes, which must contain no
+  // samples in order to be compliant files.
   SampleDescription description;
 };
 
 struct MEDIA_EXPORT MediaHeader : Box {
   DECLARE_BOX_METHODS(MediaHeader);
 
   uint64 creation_time;
   uint64 modification_time;
   uint32 timescale;
   uint64 duration;
@@ skipping 109 matching lines @@
   std::vector<TrackFragment> tracks;
   std::vector<ProtectionSystemSpecificHeader> pssh;
 };
 
 #undef DECLARE_BOX
 
 }  // namespace mp4
 }  // namespace media
 
 #endif  // MEDIA_MP4_BOX_DEFINITIONS_H_