Examine source code of ProxyContain

{
  "manifest_version": 2,
  "name": "ProxyContain",
  "version": "1.6",
  "description": "Proxy Container",
  "homepage_url": "https://github.com/dfuribez/proxycontain",
  "icons": {
    "128": "res/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "proxy@contain",
      "strict_min_version": "91.1.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "activeTab",
    "contextualIdentities",
    "cookies",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "proxy",
    "storage",
    "scripting",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "res/icon.png",
    "default_title": "Proxy Contain",
    "default_popup": "popup/popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "settings/settings.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ]
}