am 744043fc: Update FileSource to also accept a file descriptor and a range.

Merge commit '744043fcbf48c32c2051f222eca552fa2df5dfcb' into eclair-mr2-plus-aosp

* commit '744043fcbf48c32c2051f222eca552fa2df5dfcb':
  Update FileSource to also accept a file descriptor and a range.