Implement HKDF for webcrypto

content/child/webcrypto/nss/util_nss.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/nss/util_nss.h"
 
 #include "base/lazy_instance.h"
 #include "content/child/webcrypto/crypto_data.h"
 #include "content/child/webcrypto/platform_crypto.h"
 #include "crypto/nss_util.h"
@@ skipping 83 matching lines @@
 AlgorithmImplementation* CreatePlatformEcdsaImplementation() {
   // TODO(eroman): http://crbug.com/399094
   return NULL;
 }
 
 AlgorithmImplementation* CreatePlatformEcdhImplementation() {
   // TODO(eroman): http://crbug.com/399093
   return NULL;
 }
 
+AlgorithmImplementation* CreatePlatformHkdfImplementation() {
+  // HKDF is only being imlemented for BoringSSL.
+  return NULL;
+}
+
 }  // namespace webcrypto
 
 }  // namespace content