Examine source code of Better TV

{
  "manifest_version": 2,
  "version": "7.4.25",
  "name": "BetterTTV",
  "short_name": "BTTV",
  "description": "Enhances Twitch with new features, emotes, and more.",
  "author": "UnAutorDeTreaba",
  "homepage_url": "https://betterttv.com",
  "icons": {
    "128": "icon.png"
  },
  "permissions": [
    "*://*.twitch.tv/*"
  ],
  "optional_permissions": [
    "*://*.youtube.com/*"
  ],
  "web_accessible_resources": [
    "betterttv.js",
    "betterttv.css"
  ],
  "content_scripts": [
    {
      "all_frames": true,
      "js": [
        "run.js"
      ],
      "matches": [
        "*://*.twitch.tv/*"
      ],
      "exclude_matches": [
        "*://*.twitch.tv/*.html",
        "*://*.twitch.tv/*.html?*",
        "*://*.twitch.tv/*.htm",
        "*://*.twitch.tv/*.htm?*"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "applications": {
    "gecko": {
      "id": "firefox@betterttv"
    }
  }
}