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

media/base/decrypt_config.h

Index: media/base/decrypt_config.h
diff --git a/media/base/decrypt_config.h b/media/base/decrypt_config.h
index 5fca7876d330c78c76ade6c624ba00b85b49c70c..15e72da69ab9567da7bf5b076f7d444665234dd2 100644
--- a/media/base/decrypt_config.h
+++ b/media/base/decrypt_config.h
@@ -14,13 +14,23 @@ 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);
+  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:
+  scoped_array<uint8> hmac_;
+  int hmac_size_;
+
+  uint64 iv_;
+
   scoped_array<uint8> key_id_;
   int key_id_size_;