Update to current webrtc library

This is from the upstream library commit id
3326535126e435f1ba647885ce43a8f0f3d317eb, corresponding to Chromium
88.0.4290.1.

webrtc/modules/audio_processing/aec3/echo_path_variability.h

@@ -0,0 +1,37 @@
+/*
+ *  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 MODULES_AUDIO_PROCESSING_AEC3_ECHO_PATH_VARIABILITY_H_
+#define MODULES_AUDIO_PROCESSING_AEC3_ECHO_PATH_VARIABILITY_H_
+
+namespace webrtc {
+
+struct EchoPathVariability {
+  enum class DelayAdjustment {
+    kNone,
+    kBufferFlush,
+    kNewDetectedDelay
+  };
+
+  EchoPathVariability(bool gain_change,
+                      DelayAdjustment delay_change,
+                      bool clock_drift);
+
+  bool AudioPathChanged() const {
+    return gain_change || delay_change != DelayAdjustment::kNone;
+  }
+  bool gain_change;
+  DelayAdjustment delay_change;
+  bool clock_drift;
+};
+
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_AEC3_ECHO_PATH_VARIABILITY_H_