Examine source code of Web Developer Checklist

{
  "manifest_version": 2,
  "name": "Web Developer Checklist",
  "version": "2.0.3",
  "author": "Toptal",
  "description": "Analyses any web page for violations of best practices",
  "permissions": [
    "activeTab",
    "https://*/",
    "http://*/"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{65bf4dd0-b6df-44f7-9285-cb5545037d80}"
    }
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Alt+W"
      }
    }
  },
  "browser_action": {
    "default_icon": {
      "19": "icon-19.png",
      "48": "icon-48.png",
      "64": "icon-64.png",
      "128": "icon-128.png"
    },
    "default_popup": "popup.html",
    "default_title": "Web Developer Checklist"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "icons": {
    "19": "icon-19.png",
    "48": "icon-48.png",
    "64": "icon-64.png",
    "128": "icon-128.png"
  }
}