Add utf_string_conversions to base namespace.

chrome/browser/google/google_update_settings_posix.cc

Index: chrome/browser/google/google_update_settings_posix.cc
diff --git a/chrome/browser/google/google_update_settings_posix.cc b/chrome/browser/google/google_update_settings_posix.cc
index f593a9ec07020fbad52849a2ce415c15c38e2983..1aeb455646a8dae83b960f2107e6974d955ff91c 100644
--- a/chrome/browser/google/google_update_settings_posix.cc
+++ b/chrome/browser/google/google_update_settings_posix.cc
@@ -65,7 +65,7 @@ bool GoogleUpdateSettings::SetMetricsId(const std::wstring& client_id) {
     return false;
 
   // Since user has consented, write the metrics id to the file.
-  google_update::posix_guid() = WideToASCII(client_id);
+  google_update::posix_guid() = base::WideToASCII(client_id);
   return GoogleUpdateSettings::SetCollectStatsConsent(true);
 }