Added basic framework for AEC3 in the audio processing module

webrtc/modules/audio_processing/BUILD.gn

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("//build/config/arm.gni")
 import("//third_party/protobuf/proto_library.gni")
 import("../../build/webrtc.gni")
 
 declare_args() {
   # Disables the usual mode where we trust the reported system delay
   # values the AEC receives. The corresponding define is set appropriately
   # in the code, but it can be force-enabled here for testing.
   aec_untrusted_delay_for_testing = false
 }
 
 rtc_static_library("audio_processing") {
   sources = [
     "aec/aec_core.cc",
     "aec/aec_core.h",
     "aec/aec_core_optimized_methods.h",
     "aec/aec_resampler.cc",
     "aec/aec_resampler.h",
     "aec/echo_cancellation.cc",
     "aec/echo_cancellation.h",
+    "aec3/echo_canceller3.cc",
+    "aec3/echo_canceller3.h",
     "aecm/aecm_core.cc",
     "aecm/aecm_core.h",
     "aecm/echo_control_mobile.cc",
     "aecm/echo_control_mobile.h",
     "agc/agc.cc",
     "agc/agc.h",
     "agc/agc_manager_direct.cc",
     "agc/agc_manager_direct.h",
     "agc/gain_map_internal.h",
     "agc/loudness_histogram.cc",
@@ skipping 509 matching lines @@
       ]
 
       deps = [
         ":audioproc_debug_proto",
         "../..:webrtc_common",
         "../../base:rtc_base_approved",
       ]
     }
   }
 }