This allows Objective C(++) users to supply their own implementations of the webrtc::AudioProcessing module.
Bug: webrtc:8163
Change-Id: I2302610c9b45b2f483146d6fe7d82be419b33ee2
Reviewed-on: https://webrtc-review.googlesource.com/18180
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Commit-Queue: Sam Zackrisson <saza@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20668}