This simplifies the code and ensures we don't starve the decoder if
there are multiple output buffers queued.
Bug: webrtc:7760
Change-Id: I42c31f5045fca96847001260b8796d6756900d0f
Reviewed-on: https://webrtc-review.googlesource.com/5522
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20161}