[PPAPI] Implement media stream video track API

ppapi/shared_impl/media_stream_frame_buffer.cc

+// Copyright (c) 2014 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.
+
+#include "ppapi/shared_impl/media_stream_frame_buffer.h"
+
+#include "ppapi/c/pp_errors.h"
+
+namespace ppapi {
+
+MediaStreamFrameBuffer::Delegate::~Delegate() {}
+
+void MediaStreamFrameBuffer::Delegate::OnNewFrameEnqueued() {
+}
+
+MediaStreamFrameBuffer::MediaStreamFrameBuffer(Delegate* delegate)
+   : delegate_(delegate),
+     frame_size_(0),
+     number_of_frames_(0) {
+  DCHECK(delegate_);
+}
+
+MediaStreamFrameBuffer::~MediaStreamFrameBuffer() {
+}
+
+bool MediaStreamFrameBuffer::SetFrames(
+    int32_t number_of_frames,
+    int32_t frame_size,
+    scoped_ptr<base::SharedMemory> shm,
+    bool enqueue_all_frames) {
+  DCHECK(shm);
+  DCHECK(!shm_);
+  DCHECK_GT(number_of_frames, 0);
+  DCHECK_GT(frame_size, static_cast<int32_t>(sizeof(MediaStreamFrame::Header)));
+  DCHECK_EQ(frame_size & 0x3, 0);
+
+  number_of_frames_ = number_of_frames;
+  frame_size_ = frame_size;
+
+  int32_t size = number_of_frames_ * frame_size;
+  shm_ = shm.Pass();
+  if (!shm_->Map(size))
+    return false;
+
+  uint8_t* p = reinterpret_cast<uint8_t*>(shm_->memory());
+  for (int32_t i = 0; i < number_of_frames; ++i) {
+    if (enqueue_all_frames)
+      frame_queue_.push_back(i);
+    frames_.push_back(reinterpret_cast<MediaStreamFrame*>(p));
+    p += frame_size_;
+  }
+  return true;
+}
+
+int32_t MediaStreamFrameBuffer::DequeueFrame() {
+  if (frame_queue_.empty())
+    return PP_ERROR_FAILED;
+  int32_t frame = frame_queue_.front();
+  frame_queue_.pop_front();
+  return frame;
+}
+
+void MediaStreamFrameBuffer::EnqueueFrame(int32_t index) {
+  DCHECK_GE(index, 0);
+  DCHECK_LT(index, number_of_frames_);
+  frame_queue_.push_back(index);
+  delegate_->OnNewFrameEnqueued();
+}
+
+MediaStreamFrame* MediaStreamFrameBuffer::GetFramePointer(
+    int32_t index) {
+  DCHECK_GE(index, 0);
+  DCHECK_LT(index, number_of_frames_);
+  return frames_[index];
+}
+
+}  // namespace ppapi