code: public MediaHttpDownloader setContentRange(long firstBytePos, long lastBytePos) {
      Preconditions.checkArgument(lastBytePos >= firstBytePos);
      setBytesDownloaded(firstBytePos);
      this.lastBytePos = lastBytePos;
      return this;
    }
docs: Sets the content range of the next download request. Eg: bytes=firstBytePos-lastBytePos.
  
  <p>If a download was aborted mid-way due to a connection failure then users can resume the
  download from the point where it left off.
  
  <p>Use {@link #setBytesDownloaded} if you only need to specify the first byte position.
  
  @param firstBytePos The first byte position in the content range string
  @param lastBytePos The last byte position in the content range string.
  @since 1.24