Examine source code of Better Clean Twitter

{
  "manifest_version": 2,
  "name": "Better Clean Twitter",
  "description": "Remove all the annoying clutter from your Twitter.",
  "version": "1.3.2",
  "icons": {
    "16": "icon.png",
    "32": "icon.png",
    "64": "icon.png",
    "128": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "bct@presti.me"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://twitter.com/*"
      ],
      "js": [
        "js/jquery.js",
        "js/content.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Better Clean Twitter",
    "default_popup": "popup.html"
  },
  "permissions": [
    "*://twitter.com/*",
    "*://api.twitter.com/*",
    "activeTab",
    "storage",
    "tabs",
    "scripting",
    "webRequest",
    "nativeMessaging"
  ]
}