Examine source code of AS Sync

{
  "manifest_version": 2,
  "name": "AS Sync",
  "description": "Backup and restore your anime-sama.tv progress across domain changes",
  "version": "1.2.1",
  "icons": {
    "16": "/icon-16.png",
    "32": "/icon-32.png",
    "48": "/icon-48.png",
    "96": "/icon-96.png",
    "128": "/icon-128.png"
  },
  "author": "WaYyTempest",
  "homepage_url": "https://github.com/WaYyTempest/as-sync",
  "permissions": [
    "storage",
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "as-sync@anime-sama.tv",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "purposes": [],
        "is_exempt": true
      }
    }
  },
  "web_accessible_resources": [
    "injected.js"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "AS Sync",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-scripts/content.js"
      ]
    }
  ]
}