Examine source code of OurTube

{
  "manifest_version": 2,
  "name": "OurTube",
  "version": "1.3resigned1",
  "description": "Changes YouTube logo to OurTube",
  "icons": {
    "48": "48-icon.png",
    "96": "96-icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*"
      ],
      "js": [
        "OurTube.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{01dfc595-1184-42a6-b583-65d524402a46}"
    }
  }
}