Examine source code of YiNote

{
  "name": "YiNote",
  "version": "1.6.0",
  "description": "Most efficient way to take & share time-stamped notes while watching videos!",
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "browser_action": {
    "default_icon": "icons/icon-16.png"
  },
  "manifest_version": 2,
  "default_locale": "en",
  "permissions": [
    "identity",
    "storage",
    "unlimitedStorage",
    "downloads",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "vendors/browser-polyfill.js",
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*",
        "file://*/*"
      ],
      "js": [
        "vendors/youtube-iframe-api.js",
        "vendors/embedly.js",
        "vendors/browser-polyfill.js",
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "web_accessible_resources": [
    "installed.png",
    "images/facebook-48.png",
    "images/twitter-48.png",
    "images/copylink-48.png",
    "assets/fonts/msyh.ttf"
  ],
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "browser": "firefox"
}