Examine source code of ColorMeBackground

{
  "manifest_version": 3,
  "author": "LunarDebris",
  "name": "ColorMeBackground",
  "version": "1.0.3",
  "description": "White images on white background no more! Customize the background behind standalone images with a color or local image.",
  "browser_specific_settings": {
    "gecko": {
      "id": "colormebackground@lunardebris.dev",
      "strict_min_version": "153.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "file:///*"
  ],
  "icons": {
    "48": "icons/icon.svg",
    "96": "icons/icon.svg"
  },
  "action": {
    "default_title": "ColorMeBackground",
    "default_popup": "popup/popup.html",
    "default_icon": {
      "48": "icons/icon.svg",
      "96": "icons/icon.svg"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*",
        "file:///*"
      ],
      "js": [
        "common/defaults.js",
        "content/image-background.js"
      ],
      "run_at": "document_start",
      "all_frames": false
    }
  ]
}