Revert of Moved ring-buffer related files from common_audio to audio_processing"

webrtc/common_audio/audio_ring_buffer.h

 /*
- *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *  Copyright (c) 2015 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_COMMON_AUDIO_AUDIO_RING_BUFFER_H_
 #define WEBRTC_COMMON_AUDIO_AUDIO_RING_BUFFER_H_
 
-// TODO(peah): Remove as soon as all downstream dependencies are resolved.
-#include "webrtc/modules/audio_processing/utility/audio_ring_buffer.h"
+#include <stddef.h>
+#include <vector>
+
+struct RingBuffer;
+
+namespace webrtc {
+
+// A ring buffer tailored for float deinterleaved audio. Any operation that
+// cannot be performed as requested will cause a crash (e.g. insufficient data
+// in the buffer to fulfill a read request.)
+class AudioRingBuffer final {
+ public:
+  // Specify the number of channels and maximum number of frames the buffer will
+  // contain.
+  AudioRingBuffer(size_t channels, size_t max_frames);
+  ~AudioRingBuffer();
+
+  // Copies |data| to the buffer and advances the write pointer. |channels| must
+  // be the same as at creation time.
+  void Write(const float* const* data, size_t channels, size_t frames);
+
+  // Copies from the buffer to |data| and advances the read pointer. |channels|
+  // must be the same as at creation time.
+  void Read(float* const* data, size_t channels, size_t frames);
+
+  size_t ReadFramesAvailable() const;
+  size_t WriteFramesAvailable() const;
+
+  // Moves the read position. The forward version advances the read pointer
+  // towards the write pointer and the backward verison withdraws the read
+  // pointer away from the write pointer (i.e. flushing and stuffing the buffer
+  // respectively.)
+  void MoveReadPositionForward(size_t frames);
+  void MoveReadPositionBackward(size_t frames);
+
+ private:
+  // TODO(kwiberg): Use std::vector<std::unique_ptr<RingBuffer>> instead.
+  std::vector<RingBuffer*> buffers_;
+};
+
+}  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_AUDIO_AUDIO_RING_BUFFER_H_