Bug 573384 Reapply parts of bug 508039 that bug 547406 backed out r=KaiRo

suite/common/src/nsSessionStore.js

@@ -498,7 +498,7 @@ SessionStoreService.prototype = {
       }
       else {
         // Nothing to restore, notify observers things are complete.
-        Services.obs.notifyObservers(null, NOTIFY_WINDOWS_RESTORED, "");
+        Services.obs.notifyObservers(aWindow, NOTIFY_WINDOWS_RESTORED, "");
 
         // the next delayed save request should execute immediately
         this._lastSaveTime -= this._interval;
@@ -2699,7 +2699,7 @@ SessionStoreService.prototype = {
       this._restoreCount--;
       if (this._restoreCount == 0) {
         // This was the last window restored at startup, notify observers.
-        Services.obs.notifyObservers(null,
+        Services.obs.notifyObservers(this.windowToFocus,
           this._browserSetState ? NOTIFY_BROWSER_STATE_RESTORED : NOTIFY_WINDOWS_RESTORED,
           "");
         this._browserSetState = false;