Examine source code of Metro tab

{
  "manifest_version": 2,
  "name": "Metro tab",
  "version": "1.1.6resigned1",
  "default_locale": "en",
  "description": "__MSG_extensionDescription__",
  "developer": {
    "name": "__MSG_devName__",
    "url": "https://www.facebook.com/paradoxfm"
  },
  "homepage_url": "https://github.com/paradoxfm/firefox_metro_tab",
  "chrome_url_overrides": {
    "newtab": "metro_tab.html"
  },
  "icons": {
    "48": "icons/metro_tab.png",
    "96": "icons/metro_tab_96.png"
  },
  "page_action": {
    "browser_style": true
  },
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "permissions": [
    "storage",
    "unlimitedStorage",
    "tabs"
  ],
  "applications": {
    "gecko": {
      "strict_min_version": "56.0",
      "id": "{59006e53-dbee-4b2d-9bee-f229aafec7c3}"
    }
  }
}