Replace ToLower calls to the new format

chrome/browser/renderer_host/pepper/device_id_fetcher.cc

Index: chrome/browser/renderer_host/pepper/device_id_fetcher.cc
diff --git a/chrome/browser/renderer_host/pepper/device_id_fetcher.cc b/chrome/browser/renderer_host/pepper/device_id_fetcher.cc
index b859d2253cc277c25a5de9810c967955ed23de78..3ec57772c70b8bd1843904cb09b5c0d6190e0df6 100644
--- a/chrome/browser/renderer_host/pepper/device_id_fetcher.cc
+++ b/chrome/browser/renderer_host/pepper/device_id_fetcher.cc
@@ -159,13 +159,13 @@ void DeviceIDFetcher::ComputeOnUIThread(const std::string& salt,
   input.append(kDRMIdentifierFile);
   input.append(salt_bytes.begin(), salt_bytes.end());
   crypto::SHA256HashString(input, &id_buf, sizeof(id_buf));
-  std::string id = base::StringToLowerASCII(
+  std::string id = base::ToLowerASCII(
       base::HexEncode(reinterpret_cast<const void*>(id_buf), sizeof(id_buf)));
   input = machine_id;
   input.append(kDRMIdentifierFile);
   input.append(id);
   crypto::SHA256HashString(input, &id_buf, sizeof(id_buf));
-  id = base::StringToLowerASCII(
+  id = base::ToLowerASCII(
       base::HexEncode(reinterpret_cast<const void*>(id_buf), sizeof(id_buf)));
 
   RunCallbackOnIOThread(id, PP_OK);