Examine source code of Ez color pick

{
  "manifest_version": 2,
  "name": "Color Picker",
  "version": "1.0",
  "description": "Pick a color from any webpage and copy its hex value.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html",
    "default_title": "Pick a color"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{bae7fbb0-a7d2-4cab-af35-85df3b985128}"
    }
  }
}