Examine source code of Tab Focus Lock

{
  "manifest_version": 2,
  "name": "Tab Focus Lock",
  "version": "1.0.0",
  "description": "Keep a tab running at full speed even when it's in the background.",
  "permissions": [
    "tabs",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_start",
      "all_frames": false
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "fftabfocused@lenkura",
      "strict_min_version": "58.0"
    }
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    },
    "default_title": "Tab Focus Lock"
  }
}