title: Accessing DOM objects with few identifiers (chrome extension)
body: <p>I'm attempting to make my first ever chrome extension and I want to access the "Compose" button on Gmail via my content.js. I located the div that I want to use by inspecting the page, but I'm not sure how I can access it with Javascript since it's really deeply nested and doesn't have an ID attribute. I tried using document.querySelectorAll(".T-I.J-J5-Ji.T-I-KE.L3") and document.getElementsByClassName("T-I J-J5-Ji T-I-KE L3"), but the returned array was always empty. What am I doing wrong/what is a better way to access this element?</p>
  
  <p>This is the HTML for the element I'm trying to get
  <a href="https://i.stack.imgur.com/7RLrm.png" rel="nofollow noreferrer">here</a>.</p>
  
  <p>It would probably be easier to see the code I'm talking about by logging into Gmail (if you have one and right-clicking the "Compose" button and clicking Inspect).</p>