Examine source code of Wallabaggerini

{
  "manifest_version": 2,
  "name": "Wallabaggerini",
  "version": "0.2.1",
  "description": "Wallabag bookmarklet as page action in the URL bar",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "page_action": {
    "browser_style": true,
    "default_icon": {
      "19": "icons/icon-19.png",
      "38": "icons/icon-38.png"
    },
    "default_title": "Save to Wallabag",
    "show_matches": [
      "<all_urls>"
    ]
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "walla@baggerini"
    }
  }
}