Adding second layer of the echo canceller 3 functionality.

webrtc/modules/audio_processing/BUILD.gn

Index: webrtc/modules/audio_processing/BUILD.gn
diff --git a/webrtc/modules/audio_processing/BUILD.gn b/webrtc/modules/audio_processing/BUILD.gn
index 4dcf7d90d166c0b55bdcf69cd31e1358341d477e..dfedbee11ca304e7195a9a1df620ed37db090ae6 100644
--- a/webrtc/modules/audio_processing/BUILD.gn
+++ b/webrtc/modules/audio_processing/BUILD.gn
@@ -35,8 +35,17 @@ rtc_static_library("audio_processing") {
     "aec3/cascaded_biquad_filter.h",
     "aec3/echo_canceller3.cc",
     "aec3/echo_canceller3.h",
+    "aec3/echo_path_delay_estimator.cc",
+    "aec3/echo_path_delay_estimator.h",
+    "aec3/echo_path_variability.h",
+    "aec3/echo_remover.cc",
+    "aec3/echo_remover.h",
     "aec3/frame_blocker.cc",
     "aec3/frame_blocker.h",
+    "aec3/render_delay_buffer.cc",
+    "aec3/render_delay_buffer.h",
+    "aec3/render_delay_controller.cc",
+    "aec3/render_delay_controller.h",
     "aecm/aecm_core.cc",
     "aecm/aecm_core.h",
     "aecm/echo_control_mobile.cc",
@@ -511,8 +520,15 @@ if (rtc_include_tests) {
         "aec3/block_processor_unittest.cc",
         "aec3/cascaded_biquad_filter_unittest.cc",
         "aec3/echo_canceller3_unittest.cc",
+        "aec3/echo_path_delay_estimator_unittest.cc",
+        "aec3/echo_remover_unittest.cc",
         "aec3/frame_blocker_unittest.cc",
         "aec3/mock/mock_block_processor.h",
+        "aec3/mock/mock_echo_remover.h",
+        "aec3/mock/mock_render_delay_buffer.h",
+        "aec3/mock/mock_render_delay_controller.h",
+        "aec3/render_delay_buffer_unittest.cc",
+        "aec3/render_delay_controller_unittest.cc",
         "audio_processing_impl_locking_unittest.cc",
         "audio_processing_impl_unittest.cc",
         "audio_processing_unittest.cc",
@@ -535,6 +551,9 @@ if (rtc_include_tests) {
         "test/debug_dump_replayer.cc",
         "test/debug_dump_replayer.h",
         "test/debug_dump_test.cc",
+        "test/echo_canceller_test_tools.cc",
+        "test/echo_canceller_test_tools.h",
+        "test/echo_canceller_test_tools_unittest.cc",
         "test/test_utils.h",
         "voice_detection_unittest.cc",
       ]