Examine source code of osu!blood

{
  "manifest_version": 2,
  "name": "osu!blood",
  "author": "WoctorDho",
  "version": "1.1resigned1",
  "description": "Download beatmaps via bloodcat mirror",
  "icons": {
    "192": "icon.png"
  },
  "permissions": [
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "page_action": {
    "default_icon": "icon.png",
    "default_title": "Download beatmap via bloodcat mirror",
    "show_matches": [
      "https://osu.ppy.sh/beatmapsets/*"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a6a72c47-0469-4881-ab1b-cccdca9bca7e}"
    }
  }
}