@Override
 public boolean isIdleNow() {
   boolean idle = mVolleyRequestQueue.getSize() == 0;
   if (idle && resourceCallback != null) {
     resourceCallback.onTransitionToIdle();
   }
   return idle;
 }
 @Override
 public boolean isIdleNow() {
   long elapsed = System.currentTimeMillis() - startTime;
   boolean idle = (elapsed >= waitingTime);
   if (idle) {
     resourceCallback.onTransitionToIdle();
   }
   return idle;
 }