Bug 659777 - Check for existence of Svc.Private before accessing it [r=philikon]

services/sync/modules/engines/tabs.js

@@ -179,7 +179,7 @@ TabStore.prototype = {
     record.clientName = Clients.localName;
 
     // Don't provide any tabs to compare against and ignore the update later.
-    if (Svc.Private.privateBrowsingEnabled && !PBPrefs.get("autostart")) {
+    if (Svc.Private && Svc.Private.privateBrowsingEnabled && !PBPrefs.get("autostart")) {
       record.tabs = [];
       return record;
     }
@@ -216,7 +216,7 @@ TabStore.prototype = {
   getAllIDs: function TabStore_getAllIds() {
     // Don't report any tabs if we're in private browsing for first syncs.
     let ids = {};
-    if (Svc.Private.privateBrowsingEnabled && !PBPrefs.get("autostart"))
+    if (Svc.Private && Svc.Private.privateBrowsingEnabled && !PBPrefs.get("autostart"))
       return ids;
 
     ids[Clients.localID] = true;
@@ -333,7 +333,7 @@ TabTracker.prototype = {
   },
 
   onTab: function onTab(event) {
-    if (Svc.Private.privateBrowsingEnabled && !PBPrefs.get("autostart")) {
+    if (Svc.Private && Svc.Private.privateBrowsingEnabled && !PBPrefs.get("autostart")) {
       this._log.trace("Ignoring tab event from private browsing.");
       return;
     }

services/sync/modules/util.js

@@ -1304,12 +1304,21 @@ let _sessionCID = Services.appinfo.ID == SEAMONKEY_ID ?
 [["Form", "@mozilla.org/satchel/form-history;1", "nsIFormHistory2"],
  ["Idle", "@mozilla.org/widget/idleservice;1", "nsIIdleService"],
  ["KeyFactory", "@mozilla.org/security/keyobjectfactory;1", "nsIKeyObjectFactory"],
- ["Private", "@mozilla.org/privatebrowsing;1", "nsIPrivateBrowsingService"],
  ["Session", _sessionCID, "nsISessionStore"]
 ].forEach(function([name, contract, iface]) {
   XPCOMUtils.defineLazyServiceGetter(Svc, name, contract, iface);
 });
 
+// nsIPrivateBrowsingService is not implemented in mobile Firefox.
+// Svc.Private should just return undefined in this case instead of throwing.
+XPCOMUtils.defineLazyGetter(Svc, "Private", function() {
+  try {
+    return Cc["@mozilla.org/privatebrowsing;1"].getService(Ci["nsIPrivateBrowsingService"]);
+  } catch (e) {
+    return undefined;
+  }
+});
+
 Svc.__defineGetter__("Crypto", function() {
   let cryptoSvc;
   let ns = {};