title: How to generate google-services.json for existing Google Android project?
body: <p>In the following website, when registering for Android GCM:
  <a href="https://developers.google.com/mobile/add?platform=android&amp;cntapi=signin&amp;cntapp=Default%20Demo%20App&amp;cntpkg=com.google.samples.quickstart.signin&amp;cnturl=https:%2F%2Fdevelopers.google.com%2Fidentity%2Fsign-in%2Fandroid%2Fstart%3Fconfigured%3Dtrue&amp;cntlbl=Continue%20with%20Try%20Sign-In">https://developers.google.com/mobile/add?platform=android&amp;cntapi=signin&amp;cntapp=Default%20Demo%20App&amp;cntpkg=com.google.samples.quickstart.signin&amp;cnturl=https:%2F%2Fdevelopers.google.com%2Fidentity%2Fsign-in%2Fandroid%2Fstart%3Fconfigured%3Dtrue&amp;cntlbl=Continue%20with%20Try%20Sign-In</a></p>
  
  <p>The google-services.json file is generated here. This is required on the client side.</p>
  
  <p>How can we generate this file for <strong>existing</strong> Google Android project?</p>