rlz: Add missing base:: prefix to StringPrintf call.

rlz/mac/lib/machine_id_mac.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 <CoreFoundation/CoreFoundation.h>
 #include <IOKit/IOKitLib.h>
 #include <IOKit/network/IOEthernetInterface.h>
 #include <IOKit/network/IONetworkInterface.h>
 #include <IOKit/network/IOEthernetController.h>
 
@@ skipping 104 matching lines @@
   return serial_number_cfstring;
 }
 
 }  // namespace
 
 bool GetRawMachineId(string16* data, int* more_data) {
   uint8_t mac_address[kIOEthernetAddressSize];
 
   data->clear();
   if (GetMacAddress(mac_address, sizeof(mac_address))) {
-    *data += ASCIIToUTF16(StringPrintf("mac:%02x%02x%02x%02x%02x%02x",
+    *data += ASCIIToUTF16(base::StringPrintf("mac:%02x%02x%02x%02x%02x%02x",
         mac_address[0], mac_address[1], mac_address[2],
         mac_address[3], mac_address[4], mac_address[5]));
   }
 
   // A MAC address is enough to uniquely identify a machine, but it's only 6
   // bytes, 3 of which are manufacturer-determined. To make brute-forcing the
   // SHA1 of this harder, also append the system's serial number.
   CFStringRef serial = CopySerialNumber();
   if (serial) {
     if (!data->empty())
       *data += UTF8ToUTF16(" ");
     *data += UTF8ToUTF16("serial:") + base::SysCFStringRefToUTF16(serial);
     CFRelease(serial);
   }
 
   // On windows, this is set to the volume id. Since it's not scrambled before
   // being sent, just set it to 1.
   *more_data = 1;
   return true;
 }
 
 }  // namespace rlz_lib