Examine source code of FF Facebook Pixel Helper

{
  "manifest_version": 2,
  "name": "FF Facebook Pixel Helper",
  "version": "1.0.6",
  "description": "Unofficial Facebook Pixel Helper extension for Firefox. View all Facebook events fired on the current page.",
  "icons": {
    "48": "icons/icon-48x48.png",
    "96": "icons/icon-96x96.png"
  },
  "browser_action": {
    "default_icon": "icons/icon-32x32.png",
    "default_title": "FF Facebook Pixel Helper",
    "default_popup": "popup/build/index.html"
  },
  "background": {
    "scripts": [
      "ff-facebook-pixel-helper-background.js"
    ]
  },
  "permissions": [
    "*://*/*",
    "webRequest",
    "webNavigation"
  ]
}