Bug 668842 - Add locale to telemetry metadata; r=rstrong,tglek

toolkit/components/telemetry/TelemetryPing.js

@@ -63,6 +63,12 @@ const MEM_HISTOGRAMS = {
   "page-faults-hard": "PAGE_FAULTS_HARD"
 };
 
+function getLocale() {
+  return Cc["@mozilla.org/chrome/chrome-registry;1"].
+         getService(Ci.nsIXULChromeRegistry).
+         getSelectedLocale('global');
+}
+
 XPCOMUtils.defineLazyGetter(this, "Telemetry", function () {
   return Cc["@mozilla.org/base/telemetry;1"].getService(Ci.nsITelemetry);
 });
@@ -143,6 +149,7 @@ function getMetadata(reason) {
     appName: ai.name,
     appBuildID: ai.appBuildID,
     platformBuildID: ai.platformBuildID,
+    locale: getLocale(),
   };
 
   // sysinfo fields is not always available, get what we can.