Examine source code of Youtube Speed Tune

{
  "manifest_version": 2,
  "name": "Youtube Speed",
  "version": "0.0.1",
  "icons": {
    "16": "./icons/icon_16.png",
    "32": "./icons/icon_32.png",
    "64": "./icons/icon_64.png",
    "128": "./icons/icon_128.png",
    "256": "./icons/icon_256.png",
    "512": "./icons/icon_512.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "./scripts/content.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "./icons/icon_128.png",
    "default_popup": "./popup/popup.html"
  },
  "permissions": [
    "activeTab",
    "storage"
  ]
}