Examine source code of Add to 1Feed

{
  "version": "0.1.6",
  "name": "Add to 1Feed",
  "description": "This extension lets you add sites straight to 1Feed, your quiet place on the internet.",
  "homepage_url": "https://1feed.app/",
  "icons": {
    "16": "icons/extension-16x16.png",
    "48": "icons/extension-48x48.png",
    "128": "icons/extension-128x128.png"
  },
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/extension-128x128.png",
    "default_title": "Add to 1Feed",
    "theme_icons": [
      {
        "light": "icons/browser-action-light.svg",
        "dark": "icons/browser-action-dark.svg",
        "size": 16
      },
      {
        "light": "icons/browser-action-light.svg",
        "dark": "icons/browser-action-dark.svg",
        "size": 48
      },
      {
        "light": "icons/browser-action-light.svg",
        "dark": "icons/browser-action-dark.svg",
        "size": 128
      }
    ]
  },
  "manifest_version": 2
}