Redesign of the render buffering in AEC3

This CL centralizes the render buffering in AEC3 so that all render
buffers are updated and synchronized/aligned with the render alignment
buffer.

Bug: webrtc:8597, chromium:790905
Change-Id: I8a94e5c1f27316b6100b420eec9652ea31c1a91d
Reviewed-on: https://webrtc-review.googlesource.com/25680
Commit-Queue: Per Åhgren <peah@webrtc.org>
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20989}

modules/audio_processing/include/audio_processing.h

@@ -1154,6 +1154,8 @@ struct EchoCanceller3Config {
     size_t default_delay = 5;
     size_t down_sampling_factor = 4;
     size_t num_filters = 4;
+    size_t api_call_jitter_blocks = 26;
+    size_t min_echo_path_delay_blocks = 5;
   } delay;
 
   struct Erle {