src/main/java/com/seanchenxi/gwt/storage/client/StorageExt.java
public void clear() {
    storage.clear();
    cache.clear();
    fireEvent(StorageChangeEvent.ChangeType.CLEAR, null, null, null, null, null);
  }
public void clear() {
    storage.clear();
    cache.clear();
    fireEvent(StorageChangeEvent.ChangeType.CLEAR, null, null, null, null, null);
  }
Removes all items in the Storage, and its cache if activated

@see <a href="http://www.w3.org/TR/webstorage/#dom-storage-clear">W3C Web
Storage - Storage.clear()</a>