Examine source code of YouQuaChoo

{
  "manifest_version": 2,
  "name": "YouQuaChoo",
  "version": "1.0.0",
  "description": "Adjust quality of YouTube videos automatically",
  "permissions": [
    "storage",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "83e4ceaed6bd1e6b01f94057a0e9ab36daf39ce8@youquachoo"
    }
  },
  "content_scripts": [
    {
      "run_at": "document_start",
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "index.js"
      ]
    }
  ],
  "icons": {
    "16": "assets/external/main/16.png",
    "24": "assets/external/main/24.png",
    "32": "assets/external/main/32.png",
    "48": "assets/external/main/48.png",
    "96": "assets/external/main/96.png",
    "128": "assets/external/main/128.png"
  },
  "browser_action": {
    "default_popup": "popup/index.html",
    "default_icon": {
      "16": "assets/toolbar/fhd/16.png",
      "24": "assets/toolbar/fhd/24.png",
      "32": "assets/toolbar/fhd/32.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}