Clarify comment about safe AAC max input size, set a safer value
Avoid (theoretical) race condition on encryption key

The race could happen if the key changed for a stream was changed, e.g. a live stream
Avoid crash in native code on certain devices that misreports supported codecs

From pull-request sent to Google/ExoPlayer, "Fix for devices that report incorrect supported types. #53"
Allow player to specify HTTP user-agent
Avoid duplicated call to removeIncompleteQualities()
Avoid some devices removing all stream variants

Don't filter the streams by bitrate when MediaCodecUtil.maxH264DecodableFrameSize() returns 0
Add some clarifying comments and log statements