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

net/ssl/client_cert_store_win.cc

 // Copyright 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 "net/ssl/client_cert_store_win.h"
 
 #include <algorithm>
 #include <string>
 
 #define SECURITY_WIN32  // Needs to be defined before including security.h
@@ skipping 80 matching lines @@
                      CERT_CHAIN_FIND_BY_ISSUER_CACHE_ONLY_URL_FLAG;
   for (;;) {
     // Find a certificate chain.
     chain_context = CertFindChainInStore(cert_store,
                                          X509_ASN_ENCODING,
                                          find_flags,
                                          CERT_CHAIN_FIND_BY_ISSUER,
                                          &find_by_issuer_para,
                                          chain_context);
     if (!chain_context) {
-      if (GetLastError() != CRYPT_E_NOT_FOUND)
+      if (GetLastError() != static_cast<DWORD>(CRYPT_E_NOT_FOUND))
         DPLOG(ERROR) << "CertFindChainInStore failed: ";
       break;
     }
 
     // Get the leaf certificate.
     PCCERT_CONTEXT cert_context =
         chain_context->rgpChain[0]->rgpElement[0]->pCertContext;
     // Copy the certificate, so that it is valid after |cert_store| is closed.
     PCCERT_CONTEXT cert_context2 = NULL;
     BOOL ok = CertAddCertificateContextToStore(NULL, cert_context,
@@ skipping 104 matching lines @@
     // copy).
     if (!CertFreeCertificateContext(cert))
       return false;
   }
 
   GetClientCertsImpl(test_store.get(), request, selected_certs);
   return true;
 }
 
 }  // namespace net