Read directly from 'senc' box when 'senc' box is present

media/formats/mp4/box_definitions.cc

Index: media/formats/mp4/box_definitions.cc
diff --git a/media/formats/mp4/box_definitions.cc b/media/formats/mp4/box_definitions.cc
index b5e9f86119f67158d83a44915c79bc860a2bc500..a11c8204a94bae5062563260821d75bcc8763f87 100644
--- a/media/formats/mp4/box_definitions.cc
+++ b/media/formats/mp4/box_definitions.cc
@@ -1211,7 +1211,8 @@ bool TrackFragment::Parse(BoxReader* reader) {
          reader->MaybeReadChildren(&runs) &&
          reader->MaybeReadChild(&auxiliary_offset) &&
          reader->MaybeReadChild(&auxiliary_size) &&
-         reader->MaybeReadChild(&sdtp));
+         reader->MaybeReadChild(&sdtp) &&
+         reader->MaybeReadChild(&sample_encryption));

[kqyang, 2016/09/15 22:06:32]

This line loads 'senc' box if it is present. 

It is in the packager cl but somehow got lost when the change was integrated to
Chromium.

With this change, we will load sample encryption information from 'senc' box if
it is available; this avoids loading 'saiz' and 'saio' boxes and caching buffer
data for reading sample encryption information later.

 
   // There could be multiple SampleGroupDescription and SampleToGroup boxes with
   // different grouping types. For common encryption, the relevant grouping type