Examine source code of Youtube Speed Control

{
  "name": "Youtube Playback Speed Control",
  "version": "1.1.4",
  "manifest_version": 2,
  "description": "Control speed of the youtube playback using a keyboard. Press '+' to increase and '-' to decrease the playback speed.",
  "homepage_url": "https://github.com/Toxblh/youtube-speed-control",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "storage",
    "webRequest"
  ],
  "options_ui": {
    "page": "src/option/options.html",
    "open_in_tab": true
  },
  "background": {
    "scripts": [
      "src/background.js"
    ]
  },
  "page_action": {
    "default_title": "Control speed of the youtube playback using a keyboard.",
    "default_icon": {
      "19": "icons/icon19.png"
    }
  },
  "content_scripts": [
    {
      "all_frames": true,
      "matches": [
        "http://www.youtube.com/*",
        "https://www.youtube.com/*"
      ],
      "css": [
        "css/inject.css"
      ],
      "js": [
        "src/inject/inject.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{63eebab4-6bd0-44a0-8d79-7fefb998ebc1}"
    }
  }
}