Examine source code of Are.na

{
  "manifest_version": 2,
  "name": "Are.na",
  "description": "Assemble and connect information.",
  "version": "2.12.1",
  "browser_action": {
    "default_title": "Are.na",
    "default_icon": {
      "48": "icon-48.png",
      "128": "icon-128.png"
    }
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "storage",
    "<all_urls>"
  ],
  "icons": {
    "48": "icon-48.png",
    "96": "icon-96.png",
    "128": "icon-128.png",
    "256": "icon-256.png",
    "512": "icon-512.png"
  },
  "background": {
    "scripts": [
      "next/static/background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "next/static/inject.js"
      ],
      "match_about_blank": true
    }
  ],
  "web_accessible_resources": [
    "next/static/*",
    "index.html"
  ],
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Alt+A"
      },
      "description": "Open Are.na extension"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4245110a-2f3e-4f78-8303-10cae12384cc}"
    }
  }
}