code: static void setBackoff(Context context, int backoff) {
          final SharedPreferences prefs = getGCMPreferences(context);
          Editor editor = prefs.edit();
          editor.putInt(BACKOFF_MS, backoff);
          editor.commit();
      }
docs: Sets the backoff counter.
  <p>
  This method should be called after a GCM call fails, passing an
  exponential value.
  
  @param context application's context.
  @param backoff new backoff counter, in milliseconds.