Implement WebM subsample support

media/formats/webm/webm_crypto_helpers.h

 // Copyright 2014 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_FORMATS_WEBM_WEBM_CRYPTO_HELPERS_H_
 #define MEDIA_FORMATS_WEBM_WEBM_CRYPTO_HELPERS_H_
 
 #include <stdint.h>
 
 #include <memory>
 
 #include "media/base/decoder_buffer.h"
+#include "media/base/media_export.h"
 
 namespace media {
 
 // 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
-bool WebMCreateDecryptConfig(const uint8_t* data,
-                             int data_size,
-                             const uint8_t* key_id,
-                             int key_id_size,
-                             std::unique_ptr<DecryptConfig>* decrypt_config,
-                             int* data_offset);
+bool MEDIA_EXPORT
+WebMCreateDecryptConfig(const uint8_t* data,
+                        int data_size,
+                        const uint8_t* key_id,
+                        int key_id_size,
+                        std::unique_ptr<DecryptConfig>* decrypt_config,
+                        int* data_offset);
 
 }  // namespace media
 
 #endif  // MEDIA_FORMATS_WEBM_WEBM_CRYPTO_HELPERS_H_