Examine source code of Pyrun

{
  "manifest_version": 2,
  "name": "Pyrun",
  "description": "Integrates an IDE into Twitter, Linkedin, and Facebook and executes Python code inside your feed",
  "version": "1.5.3",
  "icons": {
    "16": "icon128t.png",
    "48": "icon128t.png",
    "128": "icon128t.png"
  },
  "web_accessible_resources": [
    "icon.png",
    "styles/pyrun.css",
    "styles/snappify.css",
    "js/pyrun.js",
    "js/twitter_modified.js",
    "js/facebook_modified.js",
    "js/linkedin_modified.js"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "js/vendor.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "js/background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "http://*.twitter.com/*",
    "https://*.twitter.com/*",
    "http://*.facebook.com/*",
    "https://*.facebook.com/*",
    "http://*.linkedin.com/*",
    "https://*.linkedin.com/*",
    "tabs",
    "activeTab",
    "scripting"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a7f7a017-2b72-4c19-a4af-de4766afa1c6}"
    }
  }
}