Examine source code of FocusTube

{
  "manifest_version": 2,
  "name": "FocusTube",
  "version": "1.0",
  "description": "Gets rid of unwanted thumbnails and enhances your focus for searching the videos you want to watch",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "FocusTube@example.com"
    }
  },
  "browser_action": {
    "default_title": "FocusTube",
    "default_popup": "popup/set_focus.html"
  },
  "permissions": [
    "webNavigation",
    "tabs",
    "activeTab",
    "storage",
    "https://www.youtube.com/*",
    "*://www.youtube.com/watch?v=*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/watch?*"
      ],
      "js": [
        "sidebarScript.js"
      ],
      "run_at": "document_end"
    }
  ],
  "icons": {
    "48": "icons/icon48.png"
  }
}