Examine source code of Show Pocket Button

{
  "manifest_version": 3,
  "name": "Show Pocket Button",
  "version": "1.0",
  "description": "Show a pocket button on each active tab to save the web page.",
  "permissions": [
    "tabs",
    "activeTab",
    "scripting"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "icons/pocket-128.png",
        "icons/cross-128.png"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "showpocketbutton@github.io"
    }
  }
}