Examine source code of Color Picker & Eyedropper: Contrast Checker

{
  "manifest_version": 3,
  "name": "Color Picker & Eyedropper: Contrast Checker",
  "short_name": "ImgColorPicker",
  "version": "1.0.0",
  "browser_specific_settings": {
    "gecko": {
      "id": "imgcolorpicker@techinterval.com",
      "strict_min_version": "128.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "description": "Eyedropper color picker with instant WCAG + APCA contrast. Grab HEX, RGB, HSL from any page or image. OKLab palettes, .ase export.",
  "homepage_url": "https://imgcolorpicker.org/",
  "permissions": [
    "activeTab",
    "storage",
    "scripting"
  ],
  "optional_permissions": [
    "downloads"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_title": "Pick a color and check its contrast",
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  },
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "commands": {
    "pick-color": {
      "suggested_key": {
        "default": "Alt+Shift+C"
      },
      "description": "Pick a color from the page"
    }
  }
}