Motown: Remove LPCM optimizations, fix prepare, add flush, add ActiveMultistreamSink model/stage

services/media/framework/models/lpcm_frame_buffer.h

-// Copyright 2016 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 MOJO_MEDIA_MODELS_LPCM_FRAME_BUFFER_H_
-#define MOJO_MEDIA_MODELS_LPCM_FRAME_BUFFER_H_
-
-#include <cstdint>
-#include <functional>
-
-#include "base/logging.h"
-
-namespace mojo {
-namespace media {
-
-// References an LPCM frame buffer and implements advancement through it.
-class LpcmFrameBuffer {
- public:
-  using ExhaustedCallback = std::function<void()>;
-
-  LpcmFrameBuffer();
-
-  ~LpcmFrameBuffer();
-
-  void set_bytes_per_frame(uint32_t bytes_per_frame) {
-    bytes_per_frame_ = bytes_per_frame;
-  }
-
-  uint32_t bytes_per_frame() const {
-    return bytes_per_frame_;
-  }
-
-  // The remaining frame buffer.
-  void* buffer() const {
-    return remaining_buffer_;
-  }
-
-  // The remaining number of frames accommodated by the frame buffer.
-  uint64_t frame_count() const {
-    return remaining_frame_count_;
-  }
-
-  // Resets the buffer and frame.
-  void Reset() {
-    remaining_buffer_ = nullptr;
-    remaining_frame_count_ = 0;
-    exhausted_callback_ = nullptr;
-  }
-
-  // Sets the buffer and frame count.
-  void Set(
-      void* buffer,
-      uint64_t frame_count,
-      ExhaustedCallback exhausted_callback = nullptr) {
-    remaining_buffer_ = buffer;
-    remaining_frame_count_ = frame_count;
-    exhausted_callback_ = exhausted_callback;
-  }
-
-  // Updates buffer and frame_count to reflect use of the buffer.
-  void Advance(uint64_t frame_count) {
-    DCHECK(remaining_buffer_);
-    DCHECK(frame_count <= remaining_frame_count_);
-    remaining_buffer_ = reinterpret_cast<uint8_t*>(remaining_buffer_) +
-        (frame_count * bytes_per_frame_);
-    remaining_frame_count_ -= frame_count;
-    if (remaining_frame_count_ == 0 && exhausted_callback_ != nullptr) {
-      exhausted_callback_();
-      exhausted_callback_ = nullptr;
-    }
-  }
-
- private:
-  uint32_t bytes_per_frame_;
-  void* remaining_buffer_;
-  uint64_t remaining_frame_count_;
-  ExhaustedCallback exhausted_callback_;
-};
-
-}  // namespace media
-}  // namespace mojo
-
-#endif // MOJO_MEDIA_MODELS_LPCM_FRAME_BUFFER_H_