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
The tests are similar because MpdWriter uses MpdBuilder.
Also changing tests and enabling them in mpd_builder_unittest.cc.
Change-Id: I76a8cfca27c390a039de765231c76d083c3ca26b