Replace ToLower calls to the new format

components/user_prefs/tracked/pref_hash_calculator.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 "components/user_prefs/tracked/pref_hash_calculator.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/json/json_string_value_serializer.h"
@@ skipping 67 matching lines @@
 
 // Generates a device ID based on the input device ID. The derived device ID has
 // no useful properties beyond those of the input device ID except that it is
 // consistent with previous implementations.
 // TODO(gab): Remove this once UMA reports for
 // Settings.TrackedPreferenceMigratedLegacyDeviceId become insignificant.
 std::string GenerateDeviceIdLikePrefMetricsServiceDid(
     const std::string& original_device_id) {
   if (original_device_id.empty())
     return std::string();
-  return base::StringToLowerASCII(
+  return base::ToLowerASCII(
       GetDigestString(original_device_id, "PrefMetricsService"));
 }
 
 }  // namespace
 
 PrefHashCalculator::PrefHashCalculator(const std::string& seed,
                                        const std::string& device_id)
     : seed_(seed),
       device_id_(device_id),
       legacy_device_id_(GenerateDeviceIdLikePrefMetricsServiceDid(device_id)) {
@@ skipping 17 matching lines @@
                          digest_string)) {
     return VALID;
   }
   if (VerifyDigestString(seed_,
                          GetMessage(legacy_device_id_, path, value_as_string),
                          digest_string)) {
     return VALID_SECURE_LEGACY;
   }
   return INVALID;
 }