Refactor WebCrypto code

content/child/webcrypto/webcrypto_util.cc

 // 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.
 
 #include "content/child/webcrypto/webcrypto_util.h"
 
 #include "base/base64.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "content/child/webcrypto/status.h"
@@ skipping 173 matching lines @@
     default:
       return false;
   }
 }
 
 bool ContainsKeyUsages(blink::WebCryptoKeyUsageMask a,
                        blink::WebCryptoKeyUsageMask b) {
   return (a & b) == b;
 }
 
+// TODO(eroman): Move this helper to WebCryptoKey.
+bool KeyUsageAllows(const blink::WebCryptoKey& key,
+                    const blink::WebCryptoKeyUsage usage) {
+  return ((key.usages() & usage) != 0);
+}
+
 bool IsAlgorithmRsa(blink::WebCryptoAlgorithmId alg_id) {
   return alg_id == blink::WebCryptoAlgorithmIdRsaOaep ||
          alg_id == blink::WebCryptoAlgorithmIdRsaSsaPkcs1v1_5;
 }
 
 bool IsAlgorithmAsymmetric(blink::WebCryptoAlgorithmId alg_id) {
   // TODO(padolph): include all other asymmetric algorithms once they are
   // defined, e.g. EC and DH.
   return IsAlgorithmRsa(alg_id);
 }
 
 }  // namespace webcrypto
 
 }  // namespace content