title: How to open the correct devtools console to see output from an extension script?
body: <p>I am trying to test sample code for web extension for browsers.
  But, it doesn't work. I checked the console for Google Chrome and also for Firefox. It doesn't print anything. The following is my code:</p>
  
  <p><em>manifest.json</em>:</p>
  
  <pre><code>{
      "description": "Demonstrating webRequests",
      "manifest_version": 2,
      "name": "webRequest-demo",
      "version": "1.0",
  
      "permissions": [
          "webRequest"
      ],
      "background": {
          "scripts": ["background.js"]
      }
  }
  </code></pre>
  
  <p><em>background.js</em>:</p>
  
  <pre><code>function logURL(requestDetails) {
      console.log("Loading: " + requestDetails.url);
  }
  
  chrome.webRequest.onBeforeRequest.addListener(
      logURL,
      {urls: ["&lt;all_urls&gt;"]}
  );
  console.log("Hell o extension background script executed");
  </code></pre>
  
  <p>Am I missing something?</p>