Examine source code of YouTube Speed Controllers

{
  "manifest_version": 2,
  "name": "YouTube Speed Controller",
  "version": "1.0",
  "description": "Allows the user to control playback speed on YouTube videos.",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon16.png",
      "48": "icon48.png",
      "128": "icon128.png"
    }
  },
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{3cc9a680-65a6-4f32-88a2-2a52143b871e}"
    }
  }
}