[webcrypto] Add symmetric key export for NSS and OpenSSL.

content/renderer/webcrypto/webcrypto_impl_nss.cc

Index: content/renderer/webcrypto/webcrypto_impl_nss.cc
diff --git a/content/renderer/webcrypto/webcrypto_impl_nss.cc b/content/renderer/webcrypto/webcrypto_impl_nss.cc
index bf6fcdac8179fcba8f65c315b3ee54ed6803d62b..36ffad457375352abe5e8448e7df7c5150b16c25 100644
--- a/content/renderer/webcrypto/webcrypto_impl_nss.cc
+++ b/content/renderer/webcrypto/webcrypto_impl_nss.cc
@@ -324,6 +324,32 @@ bool ImportKeyInternalRaw(
   return true;
 }
 
+bool ExportKeyInternalRaw(
+    const blink::WebCryptoKey& key,
+    blink::WebArrayBuffer* buffer) {
+
+  DCHECK(key.handle());
+  DCHECK(buffer);
+
+  if (key.type() != blink::WebCryptoKeyTypeSecret || !key.extractable())
+    return false;
+
+  SymKeyHandle* const sym_key = reinterpret_cast<SymKeyHandle*>(key.handle());
+
+  if (PK11_ExtractKeyValue(sym_key->key()) != SECSuccess)
+    return false;
+
+  SECItem* const key_data = PK11_GetKeyData(sym_key->key());
+  if (!key_data)
+    return false;
+  DCHECK(key_data->data);
+
+  *buffer = blink::WebArrayBuffer::create(key_data->len, 1);
+  memcpy(buffer->data(), key_data->data, key_data->len);
+
+  return true;
+}
+
 typedef scoped_ptr<CERTSubjectPublicKeyInfo,
                    crypto::NSSDestroyer<CERTSubjectPublicKeyInfo,
                                         SECKEY_DestroySubjectPublicKeyInfo> >
@@ -826,8 +852,7 @@ bool WebCryptoImpl::ExportKeyInternal(
     blink::WebArrayBuffer* buffer) {
   switch (format) {
     case blink::WebCryptoKeyFormatRaw:
-      // TODO(padolph): Implement raw export
-      return false;
+      return ExportKeyInternalRaw(key, buffer);
     case blink::WebCryptoKeyFormatSpki:
       return ExportKeyInternalSpki(key, buffer);
     case blink::WebCryptoKeyFormatPkcs8: