Convert remaining StringToLowerASCII to ToLowerASCII

google_apis/gcm/engine/gservices_settings.cc

Index: google_apis/gcm/engine/gservices_settings.cc
diff --git a/google_apis/gcm/engine/gservices_settings.cc b/google_apis/gcm/engine/gservices_settings.cc
index c50f3e89a33697f9d4449ad2fa06a47f4ce1e264..6621ff88cc362d9ffead64eb293719ec83b1e894 100644
--- a/google_apis/gcm/engine/gservices_settings.cc
+++ b/google_apis/gcm/engine/gservices_settings.cc
@@ -198,7 +198,7 @@ std::string GServicesSettings::CalculateDigest(const SettingsMap& settings) {
       reinterpret_cast<const unsigned char*>(&data[0]), data.size(), hash);
   std::string digest =
       kDigestVersionPrefix + base::HexEncode(hash, base::kSHA1Length);
-  digest = base::StringToLowerASCII(digest);
+  digest = base::ToLowerASCII(digest);
   return digest;
 }