Examine source code of Developer Excuses

{
  "manifest_version": 2,
  "name": "Developer Excuses",
  "short_name": "developer-excuses",
  "description": "Overrides your new tabs with a random developer excuse over a beautiful photo background",
  "version": "1.0.0",
  "homepage_url": "https://github.com/ayltai/developer-excuses-webextension",
  "author": "Alan Tai",
  "applications": {
    "gecko": {
      "id": "{81ed2d81-8d08-4678-ac67-4db4405e5853}",
      "strict_min_version": "58.0"
    }
  },
  "icons": {
    "16": "icon.svg",
    "24": "icon.svg",
    "32": "icon.svg",
    "48": "icon.svg",
    "64": "icon.svg",
    "72": "icon.svg",
    "96": "icon.svg",
    "128": "icon.svg",
    "144": "icon.svg",
    "192": "icon.svg",
    "256": "icon.svg",
    "512": "icon.svg"
  },
  "permissions": [
    "storage",
    "tabs",
    "https://unsplash-api-proxy.appspot.com/*"
  ],
  "chrome_url_overrides": {
    "newtab": "index.html"
  }
}