Examine source code of recall

{
  "name": "recall",
  "description": "a radio cell for reading and scanning pages.",
  "version": "0.1.2",
  "manifest_version": 2,
  "content_scripts": [
    {
      "matches": [
        "https://mercury.com/*"
      ],
      "js": [
        "cash.js"
      ]
    },
    {
      "matches": [
        "https://*.youtube.com/feed/history"
      ],
      "js": [
        "channel.js"
      ]
    },
    {
      "matches": [
        "https://twitter.com/*"
      ],
      "js": [
        "chirp.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{0934ee54-bbbb-4117-8f0d-c0e32423fecf}"
    }
  }
}