[webcrypto] Add JWK symmetric key AES-KW unwrap for NSS.

content/child/webcrypto/platform_crypto_openssl.cc

Index: content/child/webcrypto/platform_crypto_openssl.cc
diff --git a/content/child/webcrypto/platform_crypto_openssl.cc b/content/child/webcrypto/platform_crypto_openssl.cc
index d10c8b3a3bfa572a32845755754f5cff77e24d49..78054e313843f313d6c3a6c97033f585a7f677b5 100644
--- a/content/child/webcrypto/platform_crypto_openssl.cc
+++ b/content/child/webcrypto/platform_crypto_openssl.cc
@@ -403,6 +403,13 @@ Status UnwrapSymKeyAesKw(const CryptoData& wrapped_key_data,
   return Status::ErrorUnsupported();
 }
 
+Status DecryptAesKw(SymKey* key,
+                    const CryptoData& data,
+                    blink::WebArrayBuffer* buffer) {
+  // TODO(eroman): http://crbug.com/267888
+  return Status::ErrorUnsupported();
+}
+
 Status WrapSymKeyRsaEs(PublicKey* wrapping_key,
                        SymKey* key,
                        blink::WebArrayBuffer* buffer) {