Examine source code of Study Mode: YouTube

{
  "manifest_version": 2,
  "name": "Study Mode: YouTube",
  "version": "1.0",
  "description": "Enhance your YouTube study sessions, no more distractions.",
  "icons": {
    "48": "icons/toolbar-icon48.png",
    "128": "icons/toolbar-icon128.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/toolbar-icon48.png",
    "default_title": "Study Mode: YouTube",
    "default_popup": "popup/toolbar-menu.html"
  }
}