Move more string_util functions to base namespace.

sync/util/get_session_name_mac.mm

 // 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 "sync/util/get_session_name_mac.h"
 
 #include <sys/sysctl.h>
 #import <SystemConfiguration/SCDynamicStoreCopySpecific.h>
 
 #include "base/mac/scoped_cftyperef.h"
@@ skipping 18 matching lines @@
       SCDynamicStoreCopyComputerName(store.get(), NULL));
   if (computer_name.get())
     return base::SysCFStringRefToUTF8(computer_name.get());
 
   // If all else fails, return to using a slightly nicer version of the
   // hardware model.
   char modelBuffer[256];
   size_t length = sizeof(modelBuffer);
   if (!sysctlbyname("hw.model", modelBuffer, &length, NULL, 0)) {
     for (size_t i = 0; i < length; i++) {
-      if (IsAsciiDigit(modelBuffer[i]))
+      if (base::IsAsciiDigit(modelBuffer[i]))
         return std::string(modelBuffer, 0, i);
     }
     return std::string(modelBuffer, 0, length);
   }
   return "Unknown";
 }
 
 }  // namespace internal
 }  // namespace syncer