Examine source code of WatchThis!

{
  "manifest_version": 2,
  "name": "WatchThis!",
  "description": "Recommend YouTube videos directly to your friends' feeds.",
  "version": "1.0.9",
  "icons": {
    "128": "icon/128.png"
  },
  "content_security_policy": "script-src 'self'; object-src 'self'; connect-src 'self' https://pb.watch-this.app https://www.youtube.com https://i.ytimg.com;",
  "key": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqEroWuufzW7V6vVwF8s5mOlEaqD2WkC+nqhiU5VGiLWdGf6GvG71oAhZ61xOpiR2pnftdHP97Ezj9gq1H6O6/2r+FMD9NJqHDuuAsI93nlupQEK6mHxOt/V47VNrA55CN3cifc2+eXev8k8aB+2Hem7OyhxNLPptcnkwdEo/8ha/G4jTzmSUGu489rHNhUp+QtJ3F9BPNg4DXNddIGF5iJY7yI1M/jzDKNtc+F4+Ot/m1CxuJdFLLyzrxxIRaGfbWdVYjSnK+0YJdYI5me0dCMctTwXY2raT8WKHNVs/bCqS21BHznHlmfwmXm9Vyf4ejhE+sqqVAPv3/eq34O8MEQIDAQAB",
  "permissions": [
    "storage",
    "identity",
    "*://*.youtube.com/*",
    "https://pb.watch-this.app/*"
  ],
  "web_accessible_resources": [
    "/icon/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b43141bf-c568-49c8-aca7-c3f0f936eab8}",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "WatchThis",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "run_at": "document_idle",
      "js": [
        "content-scripts/content.js"
      ]
    }
  ]
}