Redesign of the render buffering in AEC3

This CL centralizes the render buffering in AEC3 so that all render
buffers are updated and synchronized/aligned with the render alignment
buffer.

Bug: webrtc:8597, chromium:790905
Change-Id: I8a94e5c1f27316b6100b420eec9652ea31c1a91d
Reviewed-on: https://webrtc-review.googlesource.com/25680
Commit-Queue: Per Åhgren <peah@webrtc.org>
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20989}

modules/audio_processing/aec3/vector_buffer.h

@@ -0,0 +1,54 @@
+/*
+ *  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_VECTOR_BUFFER_H_
+#define MODULES_AUDIO_PROCESSING_AEC3_VECTOR_BUFFER_H_
+
+#include <vector>
+
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+
+// Struct for bundling a circular buffer of one dimensional vector objects
+// together with the read and write indices.
+struct VectorBuffer {
+  VectorBuffer(size_t size, size_t height);
+  ~VectorBuffer();
+
+  size_t IncIndex(size_t index) {
+    return index < buffer.size() - 1 ? index + 1 : 0;
+  }
+
+  size_t DecIndex(size_t index) {
+    return index > 0 ? index - 1 : buffer.size() - 1;
+  }
+
+  size_t OffsetIndex(size_t index, int offset) {
+    RTC_DCHECK_GE(buffer.size(), offset);
+    return (buffer.size() + index + offset) % buffer.size();
+  }
+
+  void UpdateWriteIndex(int offset) { write = OffsetIndex(write, offset); }
+  void IncWriteIndex() { write = IncIndex(write); }
+  void DecWriteIndex() { write = DecIndex(write); }
+  void UpdateReadIndex(int offset) { read = OffsetIndex(read, offset); }
+  void IncReadIndex() { read = IncIndex(read); }
+  void DecReadIndex() { read = DecIndex(read); }
+
+  size_t size;
+  std::vector<std::vector<float>> buffer;
+  size_t write = 0;
+  size_t read = 0;
+};
+
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_AEC3_VECTOR_BUFFER_H_