Examine source code of EnvSwitcher

{
  "manifest_version": 2,
  "name": "Environment Switcher",
  "version": "1.1",
  "description": "Switch between development and production environments with visual indicators",
  "permissions": [
    "storage",
    "tabs",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "js/content.js"
      ],
      "css": [
        "css/content.css"
      ]
    }
  ],
  "commands": {
    "switch-environment": {
      "suggested_key": {
        "default": "Ctrl+Shift+S",
        "mac": "Command+Shift+S"
      },
      "description": "Switch between environments"
    }
  },
  "options_ui": {
    "page": "html/options.html",
    "open_in_tab": true
  },
  "browser_action": {
    "default_popup": "html/popup.html",
    "default_icon": {
      "16": "images/icon_16x16.png",
      "48": "images/icon_48x48.png",
      "128": "images/icon_128x128.png"
    }
  },
  "icons": {
    "16": "images/icon_16x16.png",
    "48": "images/icon_48x48.png",
    "128": "images/icon_128x128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "environment-switcher@example.com",
      "strict_min_version": "58.0"
    }
  }
}