We no longer do sanity checks based on "hdlr" tags in .mp4 files. Pretty soon...

We no longer do sanity checks based on "hdlr" tags in .mp4 files. Pretty soon we'll play any bytestream that even vaguely resembles the spec...

Change-Id: I43e05404860d8856b8aa566cc9b256bb3fa57e6f
related-to-bug: 2483328