am f0eab98c: am a063cd64: Merge "Instead of asserting, publish no tracks if an MP3Extractor is used on non-mp3 content." into gingerbread

Merge commit 'f0eab98c4ef7449eb5a5ef659cd794e0003216b3'

* commit 'f0eab98c4ef7449eb5a5ef659cd794e0003216b3':
  Instead of asserting, publish no tracks if an MP3Extractor is used on non-mp3 content.