Examine source code of RedditBooru

{
  "manifest_version": 2,
  "author": "Matt Hackmann <matt@dxprog.com>",
  "name": "RedditBooru",
  "description": "Use RedditBooru to check for reposts and rehost images from your favorite browser.",
  "version": "2.1.3resigned1",
  "permissions": [
    "contextMenus",
    "https://redditbooru.com/*"
  ],
  "icons": {
    "48": "icon.png",
    "128": "icon128.png"
  },
  "background": {
    "persistent": true,
    "scripts": [
      "reddit-booru.js"
    ]
  },
  "applications": {
    "gecko": {
      "id": "jid1-ud8I7tLgCJzpTg@jetpack",
      "strict_min_version": "42.0"
    }
  }
}