Examine source code of Web Annotation Discovery

{
  "name": "Web Annotation Discovery",
  "version": "0.1.0",
  "manifest_version": 2,
  "icons": {
    "48": "assets/icon/icon48.png",
    "96": "assets/icon/icon96.png",
    "128": "assets/icon/icon128.png",
    "256": "assets/icon/icon256.png",
    "512": "assets/icon/icon.svg"
  },
  "browser_action": {
    "default_icon": "assets/icon/icon.svg",
    "default_popup": "popup/index.html"
  },
  "background": {
    "scripts": [
      "webextension-polyfill.js",
      "background/index.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_script/index.js"
      ],
      "css": [
        "content_script/style.css"
      ]
    }
  ],
  "permissions": [
    "alarms",
    "<all_urls>",
    "contextMenus",
    "notifications",
    "webNavigation",
    "webRequest"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "web-annotation-discovery@extension"
    }
  }
}