Reland of Added ARM Neon SIMD optimizations for AEC3

webrtc/modules/audio_processing/aec3/matched_filter.h

Index: webrtc/modules/audio_processing/aec3/matched_filter.h
diff --git a/webrtc/modules/audio_processing/aec3/matched_filter.h b/webrtc/modules/audio_processing/aec3/matched_filter.h
index b9580c48f9be3725fb31caecc86c834c8d89e0b3..91df5c9d322dea6b7bf22f1eeaa8ca9dd60e63d4 100644
--- a/webrtc/modules/audio_processing/aec3/matched_filter.h
+++ b/webrtc/modules/audio_processing/aec3/matched_filter.h
@@ -22,6 +22,19 @@
 
 namespace webrtc {
 namespace aec3 {
+
+#if defined(WEBRTC_HAS_NEON)
+
+// Filter core for the matched filter that is optimized for NEON.
+void MatchedFilterCore_NEON(size_t x_start_index,
+                            float x2_sum_threshold,
+                            rtc::ArrayView<const float> x,
+                            rtc::ArrayView<const float> y,
+                            rtc::ArrayView<float> h,
+                            bool* filters_updated,
+                            float* error_sum);
+
+#endif
 
 #if defined(WEBRTC_ARCH_X86_FAMILY)