title: How to simulate killing activity to conserve memory?
body: <p>Android doc say:</p>
  
  <blockquote>
    <p>"When the system, rather than the user, shuts down an activity to conserve memory, ... "</p>
  </blockquote>
  
  <p>But how to simulate this situation?I want to debug the <code>onRestoreInstanceState(Bundle)</code> method,but don't know how to.</p>