Examine source code of MiniCalculator

{
  "manifest_version": 2,
  "name": "MiniCalculator",
  "version": "0.0.1",
  "description": "MiniCalculator",
  "icons": {
    "48": "./MiniCalculator.png",
    "96": "./MiniCalculator.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "popup/js/index.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "19": "./MiniCalculator.png",
      "38": "./MiniCalculator.png"
    },
    "default_title": "MiniCalculator",
    "default_popup": "popup/popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{457c7037-e451-4a3b-8058-269746a8ef70}"
    }
  }
}