Adding second layer of the echo canceller 3 functionality.

webrtc/modules/audio_processing/aec3/echo_remover.h

Index: webrtc/modules/audio_processing/aec3/echo_remover.h
diff --git a/webrtc/modules/audio_processing/aec3/echo_remover.h b/webrtc/modules/audio_processing/aec3/echo_remover.h
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index 0000000000000000000000000000000000000000..f7ac50cec7b14584c204a4c1886307a4d343aa9b
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+++ b/webrtc/modules/audio_processing/aec3/echo_remover.h
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+/*
+ *  Copyright (c) 2017 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.
+ */
+
+#ifndef WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_ECHO_REMOVER_H_
+#define WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_ECHO_REMOVER_H_
+
+#include <vector>
+
+#include "webrtc/base/optional.h"
+#include "webrtc/modules/audio_processing/aec3/echo_path_variability.h"
+
+namespace webrtc {
+
+// Class for removing the echo from the capture signal.
+class EchoRemover {
+ public:
+  static EchoRemover* Create(int sample_rate_hz);
+  virtual ~EchoRemover() = default;
+
+  // Removes the echo from a block of samples from the capture signal. The
+  // supplied render signal is assumed to be pre-aligned with the capture
+  // signal.
+  virtual void ProcessBlock(
+      const rtc::Optional<size_t>& echo_path_delay_samples,
+      const EchoPathVariability& echo_path_variability,
+      bool capture_signal_saturation,
+      const std::vector<std::vector<float>>& render,
+      std::vector<std::vector<float>>* capture) = 0;
+
+  // Updates the status on whether echo leakage is detected in the output of the
+  // echo remover.
+  virtual void UpdateEchoLeakageStatus(bool leakage_detected) = 0;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_ECHO_REMOVER_H_