Examine source code of Nice Playlist Generator

{
  "manifest_version": 2,
  "name": "__MSG_application_title__",
  "version": "0.3.4",
  "description": "__MSG_application_description__",
  "default_locale": "en",
  "applications": {
    "gecko": {
      "id": "rym2spotify@magdolen.sk",
      "strict_min_version": "58.0"
    }
  },
  "icons": {
    "48": "icons/rym2spotify-48.png",
    "96": "icons/rym2spotify-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.rateyourmusic.com/*",
        "*://*.sonemic.com/*"
      ],
      "js": [
        "rym2spotify-content.js"
      ]
    }
  ],
  "page_action": {
    "default_icon": {
      "19": "button/rym2spotify-19.png",
      "38": "button/rym2spotify-38.png"
    },
    "default_title": "rym2spotify",
    "default_popup": "popup/rym2spotify-popup.html",
    "browser_style": true
  },
  "background": {
    "scripts": [
      "rym2spotify-background.js"
    ]
  },
  "permissions": [
    "tabs",
    "https://api.spotify.com/",
    "https://accounts.spotify.com/"
  ]
}