Examine source code of Twitch Hide Messages

{
  "manifest_version": 2,
  "name": "Twitch Hide Messages",
  "description": "Browser extension that hides messages that start with ! on Twitch.",
  "version": "0.2",
  "icons": {
    "16": "images/ico16.png",
    "19": "images/ico19.png",
    "38": "images/ico38.png",
    "48": "images/ico48.png",
    "128": "images/ico128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.twitch.tv/*"
      ],
      "js": [
        "twitch-hide-messages.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{cff4d9c2-bebd-44f8-849f-473e16516ee7}"
    }
  }
}