Remove some uses of isdigit in net/, as it can be locale depedent.

net/ftp/ftp_network_transaction.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/ftp/ftp_network_transaction.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/compiler_specific.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 117 matching lines @@
   base::StringPiece epsv_line(response.lines[0]);
   size_t start = epsv_line.find('(');
   // If the line doesn't have a '(' or doesn't have enough characters after the
   // first '(', fail.
   if (start == base::StringPiece::npos || epsv_line.length() - start < 7)
     return false;
 
   char separator = epsv_line[start + 1];
 
   // Make sure we have "(<d><d><d>...", where <d> is not a number.
-  if (isdigit(separator) || epsv_line[start + 2] != separator ||
-      epsv_line[start + 3] != separator) {
+  if ((separator >= '0' && separator <= '9') ||
+      epsv_line[start + 2] != separator || epsv_line[start + 3] != separator) {
     return false;
   }
 
   // Skip over those characters.
   start += 4;
 
   // Make sure there's a terminal <d>.
   size_t end = epsv_line.find(separator, start);
   if (end == base::StringPiece::npos)
     return false;
@@ skipping 1211 matching lines @@
   if (!had_error_type[type]) {
     had_error_type[type] = true;
     UMA_HISTOGRAM_ENUMERATION("Net.FtpDataConnectionErrorHappened",
         type, NUM_OF_NET_ERROR_TYPES);
   }
   UMA_HISTOGRAM_ENUMERATION("Net.FtpDataConnectionErrorCount",
       type, NUM_OF_NET_ERROR_TYPES);
 }
 
 }  // namespace net