clang/win: Let some chromium_code targets build with -Wextra.

net/cert/test_root_certs_win.cc

 // Copyright (c) 2012 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 "net/cert/test_root_certs.h"
 
 #include <stdint.h>
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
@@ skipping 130 matching lines @@
   // Ensure that the default CryptoAPI functionality has been intercepted.
   // If a test certificate is never added, then no interception should
   // happen.
   g_capi_injector.Get();
 
   BOOL ok = CertAddCertificateContextToStore(
       temporary_roots_, certificate->os_cert_handle(),
       CERT_STORE_ADD_NEW, NULL);
   if (!ok) {
     // If the certificate is already added, return successfully.
-    return GetLastError() == CRYPT_E_EXISTS;
+    return GetLastError() == static_cast<DWORD>(CRYPT_E_EXISTS);
   }
 
   empty_ = false;
   return true;
 }
 
 void TestRootCerts::Clear() {
   empty_ = true;
 
   for (PCCERT_CONTEXT prev_cert =
@@ skipping 42 matching lines @@
 
 void TestRootCerts::Init() {
   empty_ = true;
   temporary_roots_ = CertOpenStore(
       CERT_STORE_PROV_MEMORY, 0, NULL,
       CERT_STORE_DEFER_CLOSE_UNTIL_LAST_FREE_FLAG, NULL);
   DCHECK(temporary_roots_);
 }
 
 }  // namespace net