Examine source code of Fix Contrast

{
  "manifest_version": 2,
  "name": "__MSG_appname__",
  "version": "1.0.3",
  "description": "__MSG_description__",
  "default_locale": "en",
  "icons": {
    "16": "icons/icon_16.png",
    "32": "icons/icon_32.png",
    "48": "icons/icon_48.png",
    "128": "icons/icon_128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "__MSG_appname__",
    "default_popup": "popup.html"
  },
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_idle",
      "all_frames": true,
      "js": [
        "contentScript.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "fix-contrast@fixally.com",
      "strict_min_version": "60.0"
    }
  }
}