Examine source code of Header Changer

{
  "manifest_version": 2,
  "name": "Header Changer",
  "description": "Change title and icon displayed on tab",
  "version": "1.1",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    },
    "default_title": "Header Changer",
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab"
  ],
  "author": "Alan Kuriakose",
  "homepage_url": "https://aln0071.github.io/"
}