[webcrypto] Add RSA public key SPKI import/export for NSS.

content/renderer/webcrypto/webcrypto_impl.cc

 // Copyright (c) 2013 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.
 
 #include "content/renderer/webcrypto/webcrypto_impl.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "third_party/WebKit/public/platform/WebArrayBuffer.h"
 #include "third_party/WebKit/public/platform/WebCryptoAlgorithm.h"
@@ skipping 138 matching lines @@
                          &key)) {
     result.completeWithError();
     return;
   }
   DCHECK(key.handle());
   DCHECK(!key.algorithm().isNull());
   DCHECK_EQ(extractable, key.extractable());
   result.completeWithKey(key);
 }
 
+void WebCryptoImpl::exportKey(
+    blink::WebCryptoKeyFormat format,
+    const blink::WebCryptoKey& key,
+    blink::WebCryptoResult result) {
+  blink::WebArrayBuffer buffer;
+  if (!ExportKeyInternal(format, key, &buffer)) {
+    result.completeWithError();
+    return;
+  }
+  result.completeWithBuffer(buffer);
+}
+
 void WebCryptoImpl::sign(
     const blink::WebCryptoAlgorithm& algorithm,
     const blink::WebCryptoKey& key,
     const unsigned char* data,
     unsigned data_size,
     blink::WebCryptoResult result) {
   DCHECK(!algorithm.isNull());
   blink::WebArrayBuffer buffer;
   if (!SignInternal(algorithm, key, data, data_size, &buffer)) {
     result.completeWithError();
@@ skipping 19 matching lines @@
                                data,
                                data_size,
                                &signature_match)) {
     result.completeWithError();
   } else {
     result.completeWithBoolean(signature_match);
   }
 }
 
 }  // namespace content