title: Android: how to determine cold start
body: <p>When app being launched, how to determine it is cold start or not?
  By cold start, I mean the app launched from the very beginning, instead of just resumed from a previous state.</p>
  
  <p><strong>:Edit:</strong>
  elaborate my question:
  I'm trying to find the app's launch mode: cold start or warm start. Cold start means the app is never launched before or not in background, so it needs a complete launch. Warm start means it is still in background, so it can resume and start faster. How to distinguish these two start modes programmatically? </p>