Introducing DecoderBuffer and general Buffer cleanup.

media/base/decoder_buffer.h

+// 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.
+
+// A specialized buffer for interfacing with audio / video decoders.
+//
+// Specifically ensures that data is aligned and padded as necessary by the
+// underlying decoding framework.  On desktop platforms this means memory is
+// allocated using FFmpeg with particular alignment and padding requirements.
+//
+// Also includes decoder specific functionality for decryption.
+
+#ifndef MEDIA_BASE_DECODER_BUFFER_H_
+#define MEDIA_BASE_DECODER_BUFFER_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "media/base/buffers.h"
+#include "media/base/decrypt_config.h"
+
+namespace media {
+
+class MEDIA_EXPORT DecoderBuffer : public Buffer {
+ public:
+  // Allocates buffer of size |buffer_size|.  If |buffer_size| is < 0, |data_|
+  // is set to a NULL ptr.  Buffer will be padded and aligned as necessary.

[scherkus (not reviewing), 2012/05/30 00:45:19]

I made a comment about this elsewhere

"data_ is set to a NULL ptr" is equivalent to calling CreateEOSBuffer() -- we
should disallow sizes < 0 and force clients to be explicit that they want an EOS
buffer

[DaleCurtis, 2012/05/30 02:28:25]

Done. Public interfaces DCHECK() this behavior.

+  explicit DecoderBuffer(int buffer_size);
+
+  // Create a DecoderBuffer whose |data_| is copied from |data|.  Buffer will be
+  // padded and aligned as necessary.
+  static scoped_refptr<DecoderBuffer> CopyFrom(const uint8* data, int size);
+
+  // Create a DecoderBuffer indicating we've reached End Of Stream.

[scherkus (not reviewing), 2012/05/30 00:45:19]

s/we've reached End Of Stream/end of stream/

also comment on what we can expect from the other accessors (i.e., GetData() ==
NULL)

[DaleCurtis, 2012/05/30 02:28:25]

Done.

+  static scoped_refptr<DecoderBuffer> CreateEOSBuffer();
+
+  // Buffer implementation.
+  virtual const uint8* GetData() const OVERRIDE;
+  virtual int GetDataSize() const OVERRIDE;
+
+  // Returns a read-write pointer to the buffer data.
+  virtual uint8* GetWritableData();
+
+  virtual const DecryptConfig* GetDecryptConfig() const;
+  virtual void SetDecryptConfig(scoped_ptr<DecryptConfig> decrypt_config);
+
+ protected:
+  DecoderBuffer(const uint8* data, int size);
+  virtual ~DecoderBuffer();
+
+ private:
+  int buffer_size_;
+  uint8* data_;
+  scoped_ptr<DecryptConfig> decrypt_config_;
+
+  // Constructor helper method for memory allocations.
+  void Initialize();
+
+  DISALLOW_COPY_AND_ASSIGN(DecoderBuffer);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_DECODER_BUFFER_H_