Examine source code of App for Messenger™

{
  "version": "0.1.6resigned1",
  "manifest_version": 2,
  "name": "App for Messenger™",
  "short_name": "messenger-web",
  "web_accessible_resources": [
    "data/panel/icons/*"
  ],
  "permissions": [
    "storage",
    "*://*.messenger.com/*"
  ],
  "background": {
    "page": "lib/chrome/background.html"
  },
  "description": "An easy-to-use and lite app for messenger",
  "homepage_url": "http://mybrowseraddon.com/messenger-web.html",
  "options_ui": {
    "chrome_style": true,
    "page": "data/options/options.html"
  },
  "browser_action": {
    "default_title": "App for Messenger™",
    "default_icon": {
      "16": "data/icons/16.png",
      "32": "data/icons/32.png",
      "48": "data/icons/48.png",
      "64": "data/icons/64.png"
    }
  },
  "content_scripts": [
    {
      "all_frames": false,
      "run_at": "document_start",
      "js": [
        "data/panel/index.js"
      ],
      "css": [
        "data/panel/index.css"
      ],
      "matches": [
        "*://*.messenger.com/*"
      ]
    }
  ],
  "icons": {
    "16": "data/icons/16.png",
    "32": "data/icons/32.png",
    "48": "data/icons/48.png",
    "64": "data/icons/64.png",
    "128": "data/icons/128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "jid1-k2Ke2x6q11huA9@jetpack"
    }
  }
}