Introduce AudioDecoderConfig to migrate away from GetAVStream().

media/base/audio_decoder_config.h

+// Copyright (c) 2011 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 MEDIA_BASE_AUDIO_DECODER_CONFIG_H_
+#define MEDIA_BASE_AUDIO_DECODER_CONFIG_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "media/base/channel_layout.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+enum AudioCodec {
+  kUnknownAudioCodec,
+  kCodecAAC,
+  kCodecMP3,
+  kCodecPCM,
+  kCodecVorbis,
+
+  // DO NOT ADD RANDOM AUDIO CODECS!
+  //
+  // The only acceptable time to add a new codec is if there is production code
+  // that uses said codec in the same CL.
+};
+
+class MEDIA_EXPORT AudioDecoderConfig {
+ public:
+  // Constructs an uninitialized object. Clients should call Initialize() with
+  // appropriate values before using.
+  AudioDecoderConfig();
+
+  // Constructs an initialized object. It is acceptable to pass in NULL for
+  // |extra_data|, otherwise the memory is copied.
+  AudioDecoderConfig(AudioCodec codec, int bits_per_channel,
+                     ChannelLayout channel_layout, int sample_rate,
+                     const uint8* extra_data, size_t extra_data_size);
+
+  ~AudioDecoderConfig();
+
+  // Resets the internal state of this object.
+  void Initialize(AudioCodec codec, int bits_per_channel,
+                  ChannelLayout channel_layout, int sample_rate,
+                  const uint8* extra_data, size_t extra_data_size);
+
+  // Returns true if this object has appropriate configuration values, false
+  // otherwise.
+  bool IsValidConfig() const;
+
+  AudioCodec codec() const;
+  int bits_per_channel() const;
+  ChannelLayout channel_layout() const;
+  int sample_rate() const;
+
+  // Optional byte data required to initialize audio decoders such as Vorbis
+  // codebooks.
+  uint8* extra_data() const;
+  size_t extra_data_size() const;
+
+ private:
+  AudioCodec codec_;
+  int bits_per_channel_;
+  ChannelLayout channel_layout_;
+  int sample_rate_;
+
+  scoped_array<uint8> extra_data_;
+  size_t extra_data_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioDecoderConfig);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_AUDIO_DECODER_CONFIG_H_