Examine source code of Wait a Minute

{
  "background": {
    "scripts": [
      "src/background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "./src/browser-polyfill.js",
        "./src/content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{0f0b2b69-0733-4738-aec9-722ce434574b}"
    }
  },
  "description": "Pause to reconsider before wasting time on the web.",
  "icons": {
    "48": "src/assets/take-a-breath48.png",
    "128": "src/assets/take-a-breath128.png"
  },
  "manifest_version": 2,
  "name": "Wait a Minute",
  "options_ui": {
    "page": "src/settings/index.html"
  },
  "permissions": [
    "alarms",
    "storage",
    "tabs"
  ],
  "version": "1.1.1",
  "web_accessible_resources": [
    "src/assets/breathe.gif"
  ]
}