Bug 986688 - Load SignInToWebsite.jsm lazily and on Nightly only. r=felipe

browser/components/nsBrowserGlue.js

@@ -12,7 +12,6 @@ const XULNS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
 
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/Services.jsm");
-Cu.import("resource:///modules/SignInToWebsite.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "AboutHome",
                                   "resource:///modules/AboutHome.jsm");
@@ -88,6 +87,11 @@ XPCOMUtils.defineLazyModuleGetter(this, "BrowserUITelemetry",
 XPCOMUtils.defineLazyModuleGetter(this, "AsyncShutdown",
                                   "resource://gre/modules/AsyncShutdown.jsm");
 
+#ifdef NIGHTLY_BUILD
+XPCOMUtils.defineLazyModuleGetter(this, "SignInToWebsiteUX",
+                                  "resource:///modules/SignInToWebsite.jsm");
+#endif
+
 const PREF_PLUGINS_NOTIFYUSER = "plugins.update.notifyUser";
 const PREF_PLUGINS_UPDATEURL  = "plugins.update.url";
 
@@ -472,7 +476,11 @@ BrowserGlue.prototype = {
     PageThumbs.init();
     NewTabUtils.init();
     BrowserNewTabPreloader.init();
-    SignInToWebsiteUX.init();
+#ifdef NIGHTLY_BUILD
+    if (Services.prefs.getBoolPref("dom.identity.enabled")) {
+      SignInToWebsiteUX.init();
+    }
+#endif
     PdfJs.init();
 #ifdef NIGHTLY_BUILD
     ShumwayUtils.init();
@@ -655,7 +663,11 @@ BrowserGlue.prototype = {
     BrowserNewTabPreloader.uninit();
     CustomizationTabPreloader.uninit();
     WebappManager.uninit();
-    SignInToWebsiteUX.uninit();
+#ifdef NIGHTLY_BUILD
+    if (Services.prefs.getBoolPref("dom.identity.enabled")) {
+      SignInToWebsiteUX.uninit();
+    }
+#endif
     webrtcUI.uninit();
   },