Examine source code of Clean Twitch

{
  "manifest_version": 2,
  "name": "Clean Twitch",
  "description": "Twitch without the clutter.",
  "version": "0.3.1",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "64": "icon/64.png",
    "96": "icon/96.png",
    "128": "icon/128.png",
    "256": "icon/256.png"
  },
  "permissions": [
    "storage",
    "declarativeNetRequest",
    "https://*.twitch.tv/*",
    "*://*.ttvnw.net/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{8f2e5b0a-9d22-4a63-a9a0-b924e19fb1e2}"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Clean Twitch",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.twitch.tv/*"
      ],
      "js": [
        "content-scripts/content.js"
      ]
    },
    {
      "matches": [
        "https://*.twitch.tv/*"
      ],
      "run_at": "document_start",
      "js": [
        "content-scripts/early.js"
      ]
    },
    {
      "matches": [
        "https://*.twitch.tv/*"
      ],
      "run_at": "document_start",
      "js": [
        "content-scripts/media-interceptor.js",
        "content-scripts/websocket-interceptor.js"
      ],
      "world": "MAIN"
    }
  ],
  "web_accessible_resources": [
    "content-scripts/content.css"
  ]
}