Implement ISO BMFF support in Media Source (try 2).

media/mp4/offset_byte_queue.cc

Index: media/mp4/offset_byte_queue.cc
diff --git a/media/mp4/offset_byte_queue.cc b/media/mp4/offset_byte_queue.cc
new file mode 100644
index 0000000000000000000000000000000000000000..862d9370b20b58ffdee8f874c5a4ba2b6c574e44
--- /dev/null
+++ b/media/mp4/offset_byte_queue.cc
@@ -0,0 +1,63 @@
+// Copyright (c) 2012 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 "media/mp4/offset_byte_queue.h"
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+
+namespace media {
+
+OffsetByteQueue::OffsetByteQueue() : buf_(NULL), size_(0), head_(0) {}
+OffsetByteQueue::~OffsetByteQueue() {}
+
+void OffsetByteQueue::Reset() {
+  queue_.Reset();
+  buf_ = NULL;
+  size_ = 0;
+  head_ = 0;
+}
+
+void OffsetByteQueue::Push(const uint8* buf, int size) {
+  queue_.Push(buf, size);
+  Sync();
+  DVLOG(4) << "Buffer pushed. head=" << head() << " tail=" << tail();
+}
+
+void OffsetByteQueue::Peek(const uint8** buf, int* size) {
+  *buf = size_ > 0 ? buf_ : NULL;
+  *size = size_;
+}
+
+void OffsetByteQueue::Pop(int count) {
+  queue_.Pop(count);
+  head_ += count;
+  Sync();
+}
+
+void OffsetByteQueue::PeekAt(int64 offset, const uint8** buf, int* size) {
+  if (offset < head() || offset >= tail()) {
+    *buf = NULL;
+    *size = 0;
+    return;
+  }
+  *buf = &buf_[offset - head()];
+  *size = tail() - offset;
+}
+
+bool OffsetByteQueue::Trim(int64 max_offset) {
+  if (max_offset < head_) return true;
+  if (max_offset > tail()) {
+    Pop(size_);
+    return false;
+  }
+  Pop(max_offset - head_);
+  return true;
+}
+
+void OffsetByteQueue::Sync() {
+  queue_.Peek(&buf_, &size_);
+}
+
+}  // namespace media