Add support for encrypted WebM files as defined in the RFC.

media/base/decrypt_config.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.
 
 #ifndef MEDIA_BASE_DECRYPT_CONFIG_H_
 #define MEDIA_BASE_DECRYPT_CONFIG_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
 // Contains all information that a decryptor needs to decrypt.
 class MEDIA_EXPORT DecryptConfig {
  public:
-  explicit DecryptConfig(const uint8* key_id, int key_id_size);
+  // The sizes are from the WebM encrypted specification. Current WebM
+  // encrypted request for comments specification is here
+  // http://wiki.webmproject.org/encryption/webm-encryption-rfc.
+  static const int kIvSize = 8;
+  static const int kKeySize = 16;
+  static const int kWebMIntegrityCheckSize = 12;
+
+  DecryptConfig(const uint8* hmac, int hmac_size,
+                uint64 iv,
+                const uint8* key_id, int key_id_size);
   ~DecryptConfig();
 
+  const uint8* hmac() const { return hmac_.get(); }
+  int hmac_size() const { return hmac_size_; }
+  uint64 iv() const { return iv_; }
   const uint8* key_id() const { return key_id_.get(); }
   int key_id_size() const { return key_id_size_; }
 
  private:
+  // HMAC defined from the WebM specification.
+  scoped_array<uint8> hmac_;
+  int hmac_size_;
+
+  // Initialization vector defined from the WebM specification.
+  uint64 iv_;
+
   scoped_array<uint8> key_id_;
   int key_id_size_;
 
   DISALLOW_COPY_AND_ASSIGN(DecryptConfig);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_DECRYPT_CONFIG_H_