Examine source code of PokemonShowdown Sync

{
  "description": "sync team of Play Pokemon Showdown ",
  "manifest_version": 2,
  "name": "PokemonShowdown Sync",
  "version": "0.2.2",
  "homepage_url": "https://github.com/ezel/PS-Sync",
  "icons": {
    "48": "icons/s1.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{aab64422-c2a5-4b32-892b-202ee48fd531}"
    }
  },
  "permissions": [
    "storage",
    "notifications",
    "https://*/*"
  ],
  "browser_action": {
    "default_icon": "icons/s1.png",
    "default_title": "PS Sync",
    "default_popup": "popup/sync.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://play.pokemonshowdown.com/*",
        "file://*/*"
      ],
      "js": [
        "content_scripts/ps-sync.js"
      ]
    }
  ]
}