Support for parsing encrypted WebM streams by src.

media/crypto/decryptor_helpers.h

Index: media/crypto/decryptor_helpers.h
diff --git a/media/crypto/decryptor_helpers.h b/media/crypto/decryptor_helpers.h
new file mode 100644
index 0000000000000000000000000000000000000000..9395fc5da0b4ca4c461538d0e97d9d0fd26764e6
--- /dev/null
+++ b/media/crypto/decryptor_helpers.h
@@ -0,0 +1,21 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.

[ddorwin, 2012/09/01 16:46:41]

Are there likely to be more functions in this file? Maybe when ISO is supported.
Having two files for one function seems odd. If this is WebM-specific - see
below - can it go in the webm helper file?

[fgalligan1, 2013/03/09 01:10:59]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_CRYPTO_DECRYPTOR_HELPERS_H_
+#define MEDIA_CRYPTO_DECRYPTOR_HELPERS_H_
+
+#include "base/basictypes.h"
+
+#include <string>

[xhwang, 2012/08/29 05:08:14]

c++ headers should go before chromium headers. So move this line before line 8.

[fgalligan1, 2013/03/09 01:10:59]

Done.

+
+namespace media {
+
+// Generates a 16 byte CTR counter block. The CTR counter block format is a
+// CTR IV appended with a CTR block counter. |iv| is an 8 byte CTR IV.
+// Returns a string of kDecryptionKeySize bytes.
+std::string GenerateCounterBlock(uint64 iv);

[ddorwin, 2012/09/01 16:46:41]

GenerateWebMCounterBlock?

[fgalligan1, 2013/03/09 01:10:59]

Done.

+
+}  // webkit_media

[xhwang, 2012/08/29 05:08:14]

This should be "// namespace media"

[fgalligan1, 2013/03/09 01:10:59]

Done.

+
+#endif  // MEDIA_CRYPTO_DECRYPTOR_HELPERS_H_