Adding full initial version of delay estimation functionality in echo canceller 3

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 dfedbee11ca304e7195a9a1df620ed37db090ae6..2684a782c3a200793197f696e368ab7c0cc79178 100644
--- a/webrtc/modules/audio_processing/BUILD.gn
+++ b/webrtc/modules/audio_processing/BUILD.gn
@@ -33,6 +33,8 @@ rtc_static_library("audio_processing") {
     "aec3/block_processor.h",
     "aec3/cascaded_biquad_filter.cc",
     "aec3/cascaded_biquad_filter.h",
+    "aec3/decimator_by_4.cc",
+    "aec3/decimator_by_4.h",
     "aec3/echo_canceller3.cc",
     "aec3/echo_canceller3.h",
     "aec3/echo_path_delay_estimator.cc",
@@ -42,6 +44,10 @@ rtc_static_library("audio_processing") {
     "aec3/echo_remover.h",
     "aec3/frame_blocker.cc",
     "aec3/frame_blocker.h",
+    "aec3/matched_filter.cc",
+    "aec3/matched_filter.h",
+    "aec3/matched_filter_lag_aggregator.cc",
+    "aec3/matched_filter_lag_aggregator.h",
     "aec3/render_delay_buffer.cc",
     "aec3/render_delay_buffer.h",
     "aec3/render_delay_controller.cc",
@@ -519,10 +525,13 @@ if (rtc_include_tests) {
         "aec3/block_framer_unittest.cc",
         "aec3/block_processor_unittest.cc",
         "aec3/cascaded_biquad_filter_unittest.cc",
+        "aec3/decimator_by_4_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/matched_filter_lag_aggregator_unittest.cc",
+        "aec3/matched_filter_unittest.cc",
         "aec3/mock/mock_block_processor.h",
         "aec3/mock/mock_echo_remover.h",
         "aec3/mock/mock_render_delay_buffer.h",