Drop DecryptConfig::data_offset_.

media/webm/webm_crypto_helpers.h

 // Copyright (c) 2013 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_WEBM_WEBM_CRYPTO_HELPERS_H_
 #define MEDIA_WEBM_WEBM_CRYPTO_HELPERS_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "media/base/decoder_buffer.h"
 
 namespace media {
 
 // TODO(xhwang): Figure out the init data type appropriately once it's spec'ed.
 // See https://www.w3.org/Bugs/Public/show_bug.cgi?id=19096 for more
 // information.
 const char kWebMEncryptInitDataType[] = "video/webm";
 
-// Returns an initialized DecryptConfig, which can be sent to the Decryptor if
-// the stream has potentially encrypted frames. Every encrypted Block has a
-// signal byte, and if the frame is encrypted, an initialization vector
-// prepended to the frame. Leaving the IV empty will tell the decryptor that the
-// frame is unencrypted. Returns NULL if |data| is invalid. Current encrypted
-// WebM request for comments specification is here
+// Fills an initialized DecryptConfig, which can be sent to the Decryptor if
+// the stream has potentially encrypted frames. Also sets |data_offset| which
+// indicates where the encrypted data starts. Leaving the IV empty will tell
+// the decryptor that the frame is unencrypted. Returns true if |data| is valid,
+// false otherwise, in which case |decrypt_config| and |data_offset| will not be
+// changed. Current encrypted WebM request for comments specification is here
 // http://wiki.webmproject.org/encryption/webm-encryption-rfc
-scoped_ptr<DecryptConfig> WebMCreateDecryptConfig(
-    const uint8* data, int data_size,
-    const uint8* key_id, int key_id_size);
+bool WebMCreateDecryptConfig(const uint8* data, int data_size,
+                             const uint8* key_id, int key_id_size,
+                             scoped_ptr<DecryptConfig>* decrypt_config,
+                             int* data_offset);
 
 }  // namespace media
 
 #endif  // MEDIA_WEBM_WEBM_CRYPT_HELPERS_H_