This CL relands the code from the CL "Process 8 kHz audio as 16 kHz internally of the audio processing module" which by mistake was reverted via a rebase in another CL. The CL changes the behavior of APM for 8 kHz so that it is internally processed as 16 kHz. Bug: webrtc:10863 Change-Id: I32a57b2d279c2134125667c19b09cfda381a33c3 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/150221 Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org> Commit-Queue: Per Åhgren <peah@webrtc.org> Cr-Commit-Position: refs/heads/master@{#28944}