Get the encoder queue in init instead of the constructor. The constructor is not always called on the same thread as init. The encoder may also be reinitialized on a different thread. Bug: webrtc:7760 Change-Id: I32a025a8bdf652ab019ac4c2ffc6be1533008925 Reviewed-on: https://webrtc-review.googlesource.com/5480 Reviewed-by: Magnus Jedvert <magjed@webrtc.org> Commit-Queue: Sami Kalliomäki <sakal@webrtc.org> Cr-Commit-Position: refs/heads/master@{#20074}