Make AudioDecoderConfig copyable.

media/crypto/aes_decryptor.cc

Index: media/crypto/aes_decryptor.cc
diff --git a/media/crypto/aes_decryptor.cc b/media/crypto/aes_decryptor.cc
index 4e0feea4674f5a86eb0c968889a36bfc32e9e077..4c3d0d7b1b72390c286cded3ed20f62428a21080 100644
--- a/media/crypto/aes_decryptor.cc
+++ b/media/crypto/aes_decryptor.cc
@@ -266,7 +266,7 @@ void AesDecryptor::CancelDecrypt(StreamType stream_type) {
   // Decrypt() calls the DecryptCB synchronously so there's nothing to cancel.
 }
 
-void AesDecryptor::InitializeAudioDecoder(scoped_ptr<AudioDecoderConfig> config,
+void AesDecryptor::InitializeAudioDecoder(const AudioDecoderConfig& config,
                                           const DecoderInitCB& init_cb) {
   // AesDecryptor does not support audio decoding.
   init_cb.Run(false);