Safe behavior of the initial echo removal in AEC3

This CL adds functionality to allow removal of any echo occurring
before the render and capture signals have been properly aligned.
The functionality is added in such a manner that the transparency
to nearend is maintained as much as possible.


Bug: webrtc:8883
Change-Id: I813cbbc4c48822e7dffcd9ab6233be4c222089de
Reviewed-on: https://webrtc-review.googlesource.com/49941
Commit-Queue: Per Åhgren <peah@webrtc.org>
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22107}

modules/audio_processing/include/audio_processing.cc

@@ -32,4 +32,5 @@ Beamforming::Beamforming(bool enabled,
       target_direction(target_direction) {}
 
 Beamforming::~Beamforming() {}
+
 }  // namespace webrtc