Examine source code of Battery Status

{
  "manifest_version": 2,
  "name": "Battery Status",
  "version": "1.1",
  "description": "Monitor battery level charging state and estimated time",
  "browser_specific_settings": {
    "gecko": {
      "id": "{8ce8eb94-72c0-4b3b-a845-249c138139b8}",
      "strict_min_version": "96.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "16": "gfx/ic16.png",
    "32": "gfx/ic32.png",
    "48": "gfx/ic48.png",
    "96": "gfx/ic96.png",
    "128": "gfx/ic128.png"
  },
  "browser_action": {
    "default_popup": "front/app.html",
    "default_icon": {
      "16": "gfx/ic16.png",
      "32": "gfx/ic32.png",
      "48": "gfx/ic48.png",
      "96": "gfx/ic96.png",
      "128": "gfx/ic128.png"
    }
  },
  "background": {
    "scripts": [
      "back/daemon.js"
    ]
  },
  "permissions": []
}