Revert "This CL is to reduce the complexity of current FIFO structure."

third_party/WebKit/Source/platform/audio/PushPullFIFO.h

Index: third_party/WebKit/Source/platform/audio/PushPullFIFO.h
diff --git a/third_party/WebKit/Source/platform/audio/PushPullFIFO.h b/third_party/WebKit/Source/platform/audio/PushPullFIFO.h
deleted file mode 100644
index 2341372f35ab452fb8814dc22208ff3c24e9cd87..0000000000000000000000000000000000000000
--- a/third_party/WebKit/Source/platform/audio/PushPullFIFO.h
+++ /dev/null
@@ -1,85 +0,0 @@
-// Copyright 2017 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef PushPullFIFO_h
-#define PushPullFIFO_h
-
-#include "platform/audio/AudioBus.h"
-#include "public/platform/WebCommon.h"
-#include "wtf/Allocator.h"
-
-namespace blink {
-
-// A configuration data container for PushPullFIFO unit test.
-struct PushPullFIFOStateForTest {
-  const size_t fifoLength;
-  const unsigned numberOfChannels;
-  const size_t framesAvailable;
-  const size_t indexRead;
-  const size_t indexWrite;
-  const unsigned overflowCount;
-  const unsigned underflowCount;
-};
-
-// PushPullFIFO class is an intermediate audio sample storage between
-// Blink-WebAudio and the renderer. The renderer's hardware callback buffer size
-// varies on the platform, but the WebAudio always renders 128 frames (render
-// quantum, RQ) thus FIFO is needed to handle the general case.
-class BLINK_PLATFORM_EXPORT PushPullFIFO {
-  USING_FAST_MALLOC(PushPullFIFO);
-  WTF_MAKE_NONCOPYABLE(PushPullFIFO);
-
- public:
-  // Maximum FIFO length. (512 render quanta)
-  static const size_t kMaxFIFOLength;
-
-  // |fifoLength| cannot exceed |kMaxFIFOLength|. Otherwise it crashes.
-  explicit PushPullFIFO(unsigned numberOfChannels, size_t fifoLength);
-  ~PushPullFIFO();
-
-  // Pushes the rendered frames by WebAudio engine.
-  //  - The |inputBus| length is 128 frames (1 render quantum), fixed.
-  //  - In case of overflow (FIFO full while push), the existing frames in FIFO
-  //    will be overwritten and |indexRead| will be forcibly moved to
-  //    |indexWrite| to avoid reading overwritten frames.
-  void push(const AudioBus* inputBus);
-
-  // Pulling |framesRequested| by the audio device thread.
-  //  - If |framesRequested| is bigger than the length of |outputBus|, it
-  //    violates SECURITY_CHECK().
-  //  - If |framesRequested| is bigger than FIFO length, it violates
-  //    SECURITY_CHECK().
-  //  - In case of underflow (FIFO empty while pull), the remaining space in the
-  //    requested output bus will be filled with silence. Thus it will fulfill
-  //    the request from the consumer without causing error, but with a glitch.
-  void pull(AudioBus* outputBus, size_t framesRequested);
-
-  size_t framesAvailable() const { return m_framesAvailable; }
-  size_t length() const { return m_fifoLength; }
-  unsigned numberOfChannels() const { return m_fifoBus->numberOfChannels(); }
-  AudioBus* bus() const { return m_fifoBus.get(); }
-
-  // For unit test. Get the current configuration that consists of FIFO length,
-  // number of channels, read/write index position and under/overflow count.
-  const PushPullFIFOStateForTest getStateForTest() const;
-
- private:
-  // The size of the FIFO.
-  const size_t m_fifoLength = 0;
-
-  RefPtr<AudioBus> m_fifoBus;
-
-  // The number of frames in the FIFO actually available for pulling.
-  size_t m_framesAvailable;
-
-  size_t m_indexRead;
-  size_t m_indexWrite;
-
-  unsigned m_overflowCount;
-  unsigned m_underflowCount;
-};
-
-}  // namespace blink
-
-#endif  // PushPullFIFO_h