Compensate for the IntelligibilityEnhancer processing delay in high bands

webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc

Index: webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc
diff --git a/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc b/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc
index 6e641a23325984bee6daab921a67c9acc959a489..fa8d1704c6775e31673c07a460d2e835fa5f1a58 100644
--- a/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc
+++ b/webrtc/modules/audio_processing/intelligibility/intelligibility_utils.cc
@@ -66,6 +66,27 @@ void GainApplier::Apply(const std::complex<float>* in_block,
   }
 }
 
+DelayBuffer::DelayBuffer(size_t delay, size_t num_channels)
+    : buffer_(num_channels, std::vector<float>(delay, 0.f)), read_index_(0u) {}
+
+DelayBuffer::~DelayBuffer() {}
+
+void DelayBuffer::Delay(float* const* data, size_t length) {
+  size_t sample_index = read_index_;
+  for (size_t i = 0u; i < buffer_.size(); ++i) {
+    sample_index = read_index_;
+    for (size_t j = 0u; j < length; ++j) {
+      float swap = data[i][j];
+      data[i][j] = buffer_[i][sample_index];
+      buffer_[i][sample_index] = swap;
+      if (++sample_index == buffer_.size()) {
+        sample_index = 0u;
+      }
+    }
+  }
+  read_index_ = sample_index;
+}
+
 }  // namespace intelligibility
 
 }  // namespace webrtc