Examine source code of Audio to MP3

{
  "version": "0.1.2resigned1",
  "manifest_version": 2,
  "name": "Audio to MP3",
  "short_name": "audio-to-mp3",
  "background": {
    "page": "lib/chrome/background.html"
  },
  "homepage_url": "http://mybrowseraddon.com/audio-to-mp3.html",
  "permissions": [
    "storage",
    "<all_urls>",
    "downloads",
    "contextMenus"
  ],
  "description": "Convert any streaming audio to MP3 and download it to your machine.",
  "page_action": {
    "default_title": "Audio to MP3",
    "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": true,
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_start",
      "exclude_globs": [
        "*://*.youtube.*/*"
      ],
      "js": [
        "data/content_script/inject.js"
      ]
    },
    {
      "all_frames": false,
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_start",
      "js": [
        "data/content_script/page.js"
      ],
      "exclude_globs": [
        "*://*.youtube.*/*"
      ],
      "css": [
        "data/content_script/page.css"
      ]
    }
  ],
  "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": "{689d714d-fc35-4d05-a3d1-9788a107f322}"
    }
  }
}