IPC to pass media data using a lock free circular fifo.

chromecast/media/cma/ipc/media_memory_chunk.h

+// Copyright 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.
+
+#ifndef CHROMECAST_MEDIA_CMA_IPC_MEDIA_MEMORY_CHUNK_H_
+#define CHROMECAST_MEDIA_CMA_IPC_MEDIA_MEMORY_CHUNK_H_
+
+#include "base/basictypes.h"
+
+namespace chromecast {
+namespace media {
+
+// MediaMemoryChunk represents a block of memory without doing any assumption
+// about the type of memory (e.g. shared memory) nor about the underlying
+// memory ownership.
+// The block of memory can be invalidated under the cover (e.g. if the derived
+// class does not own the underlying memory),
+// in that case, MediaMemoryChunk::valid() will return false.
+class MediaMemoryChunk {
+ public:
+  virtual ~MediaMemoryChunk();
+
+  // Returns the start of the block of memory.
+  virtual void* data() const = 0;
+
+  // Returns the size of the block of memory.
+  virtual size_t size() const = 0;
+
+  // Returns whether the underlying block of memory is valid.
+  // Since MediaMemoryChunk does not specify a memory ownership model,
+  // the underlying block of memory might be invalidated by a third party.
+  // In that case, valid() will return false.
+  virtual bool valid() const = 0;
+};
+
+}  // namespace media
+}  // namespace chromecast
+
+#endif  // CHROMECAST_MEDIA_CMA_IPC_MEDIA_MEMORY_CHUNK_H_