Examine source code of Maps with what3words

{
  "name": "__MSG_appName__",
  "description": "__MSG_appDescription__",
  "version": "1.3.2",
  "short_name": "__MSG_appShortName__",
  "manifest_version": 2,
  "default_locale": "en",
  "icons": {
    "16": "images/icon-16.png",
    "128": "images/icon-128.png"
  },
  "omnibox": {
    "keyword": "///"
  },
  "background": {
    "scripts": [
      "scripts/background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "19": "images/icon-19.png",
      "38": "images/icon-38.png"
    },
    "default_title": "__MSG_browserActionTitle__",
    "default_popup": "pages/popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "include_globs": [
        "https://maps.google.*/*",
        "https://google.*/maps",
        "https://google.*/maps*",
        "https://google.*/maps/*",
        "https://www.google.*/maps",
        "https://www.google.*/maps*",
        "https://www.google.*/maps/*",
        "https://google.*/*",
        "https://google.*/search",
        "https://google.*/search*",
        "https://google.*/search/*",
        "https://google.*/webhp",
        "https://google.*/webhp*",
        "https://google.*/webhp/*",
        "https://www.google.*/*",
        "https://www.google.*/search",
        "https://www.google.*/search*",
        "https://www.google.*/search/*",
        "https://www.google.*/webhp",
        "https://www.google.*/webhp*",
        "https://www.google.*/webhp/*",
        "https://www.bing.com/",
        "https://bing.com/",
        "https://www.bing.com/*",
        "https://bing.com/*",
        "https://www.bing.com/maps",
        "https://bing.com/maps",
        "https://www.bing.com/maps*",
        "https://bing.com/maps*",
        "https://bing.com/maps/*",
        "https://www.bing.com/maps/*"
      ],
      "css": [
        "styles/contentscript.css"
      ],
      "js": [
        "scripts/contentscript.js"
      ],
      "run_at": "document_end",
      "all_frames": true
    }
  ],
  "web_accessible_resources": [
    "images/*.png",
    "images/flags/*.svg"
  ],
  "permissions": [
    "webRequest",
    "storage",
    "<all_urls>"
  ]
}