A quick fix for Mac GCC.

net/base/x509_certificate.cc

 // Copyright (c) 2011 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/base/x509_certificate.h"
 
 #include <stdlib.h>
 
 #include <algorithm>
 #include <map>
@@ skipping 692 matching lines @@
     // subjectAltName dNSName: www.google.com, google.com
     {0xf5,0xc8,0x6a,0xf3,0x61,0x62,0xf1,0x3a,0x64,0xf5,0x4f,0x6d,0xc9,0x58,0x7c,0x06},
     // Subject: CN=login.yahoo.com
     // subjectAltName dNSName: login.yahoo.com
     {0x39,0x2a,0x43,0x4f,0x0e,0x07,0xdf,0x1f,0x8a,0xa3,0x05,0xde,0x34,0xe0,0xc2,0x29},
     // Subject: CN=login.yahoo.com
     // subjectAltName dNSName: login.yahoo.com
     {0x3e,0x75,0xce,0xd4,0x6b,0x69,0x30,0x21,0x21,0x88,0x30,0xae,0x86,0xa8,0x2a,0x71},
   };
 
-  if (!serial_number_.empty() && serial_number_[0] >= 0x80) {
+  if (!serial_number_.empty() &&
+      static_cast<unsigned char>(serial_number_[0]) >= 0x80) {
     // This is a negative serial number, which isn't technically allowed but
     // which probably happens. In order to avoid confusing a negative serial
     // number with a positive one once the leading zeros have been removed, we
     // disregard it.
     return false;
   }
 
   base::StringPiece serial(serial_number_);
   // Remove leading zeros.
   while (serial.size() > 1 && serial[0] == 0)
@@ skipping 53 matching lines @@
 bool X509Certificate::IsSHA1HashInSortedArray(const SHA1Fingerprint& hash,
                                               const uint8* array,
                                               size_t array_byte_len) {
   DCHECK_EQ(0u, array_byte_len % base::kSHA1Length);
   const size_t arraylen = array_byte_len / base::kSHA1Length;
   return NULL != bsearch(hash.data, array, arraylen, base::kSHA1Length,
                          CompareSHA1Hashes);
 }
 
 }  // namespace net