private synchronized void syncRemoveFromMap(@NotNull List<T> list, @NotNull CefBrowser browser, @NotNull Runnable onClear) {
      if (list.isEmpty()) {
        myMap.remove(browser);
        if (myMap.isEmpty()) {
          onClear.run();
        }
      }
    }
private synchronized void syncRemoveFromMap(@NotNull List<T> list, @NotNull CefBrowser browser, @NotNull Runnable onClear)