title: Get tab ID in order to update after creation
body: <p>When a browser creates a new tab it starts off empty and then is updated with <code>about:blank</code> or <code>about:newtab</code>. I need JavaScript to be able to update this within the extension.</p>
  
  <p>Currently I have;</p>
  
  <pre><code>browser.tabs.onCreated.addListener(handleCreated);
  browser.tabs.onUpdated.addListener(handleUpdate);
  </code></pre>
  
  <p>This allows me to know when a new tab is created and then when it is updated. After this I need to be able to update it again with something like this;</p>
  
  <pre><code> var TabReplacement = {url: 'https://mycompany.com/newtab.html'};
      browser.tabs.update(TabReplacement);
  </code></pre>
  
  <p>I just need to be able to update the tab again in order to have a custom new tab but it shouldn't affect new tabs that are created by opening links in a new tab etc. I know that it needs to trigger when the event listener is activated.</p>
  
  <p>Would you update the tab straight away or obtain the tab ID and then update via tab ID?</p>
  
  <p>TLDR; I want the same function as:</p>
  
  <pre><code>{
    "name": "My extension",
    ...
  
    "chrome_url_overrides" : {
      "about:newtab": "https://www.google.com"
    },
    ...
  }
  </code></pre>
  
  <p>Has in a Chrome manifest file but this isn't possible with edge.</p>
  
  <p>Thanks in advance :)</p>