Examine source code of Container Forcer

{
  "manifest_version": 2,
  "name": "Container Forcer",
  "version": "1.0",
  "description": "Forces container selection for new tabs. We don't want to use the default container. It's the rule. It's the law.",
  "icons": {
    "16": "icons/icon.svg",
    "32": "icons/icon.svg",
    "48": "icons/icon.svg",
    "96": "icons/icon.svg",
    "128": "icons/icon.svg"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "activeTab",
    "contextualIdentities",
    "tabs",
    "cookies",
    "webRequest",
    "<all_urls>"
  ],
  "web_accessible_resources": [
    "select-container.html"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "ledongthuc@gmail.com"
    }
  }
}