[webcrypto] Remove the TODO for NullKey().

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 28 matching lines @@
   if (new_size == buffer->byteLength())
     return;
 
   WebKit::WebArrayBuffer new_buffer =
       WebKit::WebArrayBuffer::create(new_size, 1);
   DCHECK(!new_buffer.isNull());
   memcpy(new_buffer.data(), buffer->data(), new_size);
   *buffer = new_buffer;
 }
 
-// static
-// TODO(eroman): Expose functionality in Blink instead.
-WebKit::WebCryptoKey WebCryptoImpl::NullKey() {
-  // Needs a non-null algorithm to succeed.
-  return WebKit::WebCryptoKey::create(
-      NULL, WebKit::WebCryptoKeyTypeSecret, false,
-      WebKit::WebCryptoAlgorithm::adoptParamsAndCreate(
-          WebKit::WebCryptoAlgorithmIdAesGcm, NULL), 0);
-}
-
 void WebCryptoImpl::encrypt(
     const WebKit::WebCryptoAlgorithm& algorithm,
     const WebKit::WebCryptoKey& key,
     const unsigned char* data,
     unsigned data_size,
     WebKit::WebCryptoResult result) {
   DCHECK(!algorithm.isNull());
   WebKit::WebArrayBuffer buffer;
   if (!EncryptInternal(algorithm, key, data, data_size, &buffer)) {
     result.completeWithError();
@@ skipping 129 matching lines @@
                                data,
                                data_size,
                                &signature_match)) {
     result.completeWithError();
   } else {
     result.completeWithBoolean(signature_match);
   }
 }
 
 }  // namespace content