For mpd codes, rename dash_packager to edash_packager; for media codes,
add namespace edash_packager.
Change-Id: I1120e6110c734cd02bdbe15f1cf7abddcdfdd7ea
Manifest was updated in CL 7debbbe19b158ea7377e229a17ec1d3d9d19d1b8
to point to Chromium LGKR CL 253526.
There are some API refactoring in base, which result in some code
changes in our packager source.
Change-Id: I52bf5a8a4f8fe0ebc566677efcd572332db8f618