Examine source code of Meter.ge

{
  "manifest_version": 2,
  "name": "Meter.ge",
  "version": "1.1",
  "description": "Meter.ge - latest currency exchange rates in Georgia",
  "icons": {
    "48": "icons/meter-ff.png"
  },
  "content_scripts": [
    {
      "all_frames": true,
      "match_about_blank": true,
      "matches": [
        "http://*/*",
        "https://*/*",
        "<all_urls>"
      ],
      "js": [
        "index.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "ff@meter.ge"
    }
  },
  "browser_action": {
    "default_icon": "icons/meter-ff.png",
    "default_title": "Meter.ge",
    "default_popup": "index.html"
  },
  "permissions": [
    "storage",
    "contextMenus"
  ]
}