Examine source code of YTVolume Normalizer

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "description": "__MSG_extensionDescription__",
  "default_locale": "ja",
  "version": "0.0.4",
  "homepage_url": "https://github.com/nahi-da/YTVolume-Normalizer",
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*"
      ],
      "js": [
        "content2.js"
      ],
      "all_frames": true
    }
  ],
  "browser_action": {
    "default_icon": "icons/48.png",
    "default_title": "Normalizer",
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "bg.js"
    ]
  },
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "64": "icons/64.png",
    "96": "icons/96.png",
    "128": "icons/128.png"
  },
  "permissions": [
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "ytvol-normalizer2@nahi-da.com"
    }
  }
}