Bug 561005 - Use FakeSvc to grab binary crypto if js-ctypes doesn't work [r=zpao r=mconnor]

Lazily load the binary component service onto FakeSvc if ;2 fails to register on Svc.

services/sync/modules/util.js

@@ -857,34 +857,21 @@ let FakeSvc = {
   }
 };
 
+// Use the binary WeaveCrypto (;1) if the js-ctypes version (;2) fails to load
+// by adding an alias on FakeSvc from ;2 to ;1
+Utils.lazySvc(FakeSvc, "@labs.mozilla.com/Weave/Crypto;2",
+              "@labs.mozilla.com/Weave/Crypto;1", "IWeaveCrypto");
+
 /*
  * Commonly-used services
  */
-let cryptoContractID = "@labs.mozilla.com/Weave/Crypto";
-
-{
-  let versSvc = Cc["@mozilla.org/xpcom/version-comparator;1"].
-                getService(Ci.nsIVersionComparator);
-  let appinfo = Cc["@mozilla.org/xre/app-info;1"].
-                getService(Ci.nsIXULAppInfo);
-  let platVers = appinfo.platformVersion;
-
-  if (versSvc.compare(platVers, "1.9.3a3") < 0) {
-    // use old binary component
-    cryptoContractID += ";1";
-  } else {
-    // use new JS-CTypes component
-    cryptoContractID += ";2";
-  }
-}
-
 let Svc = {};
 Svc.Prefs = new Preferences(PREFS_BRANCH);
 Svc.Obs = Observers;
 [["Annos", "@mozilla.org/browser/annotation-service;1", "nsIAnnotationService"],
  ["AppInfo", "@mozilla.org/xre/app-info;1", "nsIXULAppInfo"],
  ["Bookmark", "@mozilla.org/browser/nav-bookmarks-service;1", "nsINavBookmarksService"],
- ["Crypto", cryptoContractID, "IWeaveCrypto"],
+ ["Crypto", "@labs.mozilla.com/Weave/Crypto;2", "IWeaveCrypto"],
  ["Directory", "@mozilla.org/file/directory_service;1", "nsIProperties"],
  ["Env", "@mozilla.org/process/environment;1", "nsIEnvironment"],
  ["Favicon", "@mozilla.org/browser/favicon-service;1", "nsIFaviconService"],