Compensate for the IntelligibilityEnhancer processing delay in high bands

webrtc/modules/audio_processing/intelligibility/intelligibility_utils.h

 /*
  *  Copyright (c) 2014 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.
  */
 
@@ skipping 47 matching lines @@
   // Return the current target gain set. Modify this array to set the targets.
   float* target() { return target_.data(); }
 
  private:
   const size_t num_freqs_;
   const float relative_change_limit_;
   std::vector<float> target_;
   std::vector<float> current_;
 };
 
+// Helper class to delay a signal by an integer number of samples.
+class DelayBuffer {
+ public:
+  DelayBuffer(size_t delay, size_t num_channels);
+
+  ~DelayBuffer();
+
+  void Delay(float* const* data, size_t length);
+
+ private:
+  std::vector<std::vector<float>> buffer_;
+  size_t read_index_;
+};
+
 }  // namespace intelligibility
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_INTELLIGIBILITY_INTELLIGIBILITY_UTILS_H_