title: Chromium/chrome running headless: wait for page load when using --screenshot?
body: <p>Trying to take a screenshot using headless Chrome but it executes --screenshot before the page is loaded. On MacOS running zsh, I'm invoking it like this:</p>
  
  <pre><code>/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome https://example.com/foo.html --screenshot=/Users/myhome/foo.png
  </code></pre>
  
  <p>Is there a way to wait until the page is loaded before the screenshot is taken?</p>