@Override
 public boolean newSession(ICustomTabsCallback callback) {
   final CustomTabsSessionToken sessionToken = new CustomTabsSessionToken(callback);
   try {
     callback
         .asBinder()
         .linkToDeath(
             new IBinder.DeathRecipient() {
               @Override
               public void binderDied() {
                 cleanUpSession(sessionToken);
               }
             },
             0);
   } catch (RemoteException e) {
     return false;
   }
   return CustomTabsService.this.newSession(sessionToken);
 }
 /* package */ IBinder getBinder() {
   return mCallback.asBinder();
 }