Examine source code of Puzzle Creator

{
  "manifest_version": 2,
  "default_locale": "en",
  "name": "__MSG_ext_name__",
  "description": "__MSG_ext_description__",
  "version": "2.0.3resigned1",
  "applications": {
    "gecko": {
      "id": "puzzle-creator@mozilla.org",
      "strict_min_version": "45.0"
    }
  },
  "icons": {
    "16": "assets/icon_16.png",
    "19": "assets/icon_19.png",
    "32": "assets/icon_32.png",
    "38": "assets/icon_38.png",
    "128": "assets/icon_128.png",
    "256": "assets/icon_256.png",
    "512": "assets/icon_512.png"
  },
  "background": {
    "page": "background.html"
  },
  "options_ui": {
    "page": "options.html"
  },
  "permissions": [
    "contextMenus",
    "storage",
    "tabs",
    "https://www.google-analytics.com/*"
  ]
}