Bug 1015521: Bing translation service will now uses available credentials. r=felipe

browser/components/translation/BingTranslator.jsm

@@ -8,6 +8,7 @@ const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
 
 this.EXPORTED_SYMBOLS = [ "BingTranslation" ];
 
+Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/Log.jsm");
 Cu.import("resource://gre/modules/Promise.jsm");
 Cu.import("resource://gre/modules/Task.jsm");
@@ -327,8 +328,10 @@ let BingTokenManager = {
     let params = [
       "grant_type=client_credentials",
       "scope=" + encodeURIComponent("http://api.microsofttranslator.com"),
-      "client_id=",
-      "client_secret="
+      "client_id=" +
+      getAuthTokenParam("%BING_API_CLIENTID%", "browser.translation.bing.clientIdOverride"),
+      "client_secret=" +
+      getAuthTokenParam("%BING_API_KEY%", "browser.translation.bing.apiKeyOverride")
     ];
 
     let deferred = Promise.defer();
@@ -367,3 +370,16 @@ function escapeXML(aStr) {
              .replace("<", "&lt;", "g")
              .replace(">", "&gt;", "g");
 }
+
+/**
+ * Fetch an auth token (clientID or client secret), which may be overridden by
+ * a pref if it's set.
+ */
+function getAuthTokenParam(key, prefName) {
+  let val;
+  try {
+    val = Services.prefs.getCharPref(prefName);
+  } catch(ex) {}
+
+  return encodeURIComponent(Services.urlFormatter.formatURL(val || key));
+}