Examine source code of SelectionFile

{
  "manifest_version": 2,
  "name": "SelectionFile",
  "version": "0.1",
  "icons": {
    "48": "res/ico-sq48.png"
  },
  "permissions": [
    "activeTab",
    "menus",
    "downloads",
    "storage"
  ],
  "browser_action": {
    "default_icon": "res/ico-sq48.png",
    "default_title": "SelectionFile",
    "default_popup": "res/popup.html"
  },
  "background": {
    "scripts": [
      "res/context.js"
    ]
  },
  "options_ui": {
    "page": "options",
    "browser_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "SelectionFile@firefox.addon"
    }
  }
}