Examine source code of Work Offline (Page Only)

{
  "manifest_version": 2,
  "version": "0.1.4",
  "name": "Work Offline",
  "description": "Brings work offline and online in the web page level to your browser",
  "icons": {
    "16": "data/icons/16.png",
    "32": "data/icons/32.png",
    "48": "data/icons/48.png",
    "64": "data/icons/64.png",
    "128": "data/icons/128.png"
  },
  "homepage_url": "https://add0n.com/work-offline.html",
  "permissions": [
    "storage",
    "webRequest",
    "webRequestBlocking",
    "contextMenus",
    "notifications",
    "*://*/*",
    "ws://*/*",
    "wss://*/*"
  ],
  "background": {
    "scripts": [
      "webext.js",
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "16": "data/icons/disabled/16.png",
      "32": "data/icons/disabled/32.png",
      "48": "data/icons/disabled/48.png",
      "64": "data/icons/disabled/64.png"
    }
  },
  "web_accessible_resources": [
    "/data/offline/index.html"
  ]
}