Examine source code of emailStationery.com Toolbar

{
  "version": "3.0.29resigned1",
  "author": "BrandCo, LLC",
  "manifest_version": 2,
  "default_locale": "en",
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*",
        "https://us-mg5.mail.yahoo.com/*",
        "https://*.mail.yahoo.com/*",
        "https://outlook.office.com/*",
        "https://outlook.office365.com/*",
        "https://mail.aol.com/*",
        "https://*.mail.live.com/*",
        "https://outlook.live.com/*",
        "https://*.godaddy.com/*",
        "https://*.secureserver.net/*",
        "https://*.topproducer8i.com/*"
      ],
      "js": [
        "js/content_script.js"
      ],
      "css": [
        "css/external-style.css"
      ]
    }
  ],
  "web_accessible_resources": [
    "style.css",
    "css/external-style.css",
    "fonts/*",
    "img/tracking_mini_off.png",
    "img/tracking_mini_on.png",
    "img/ic_alarm_black_24dp_2x.png",
    "img/ic_alarm_blue_24dp_2x.png",
    "js/injector.js"
  ],
  "content_security_policy": "script-src 'self' https://ajax.googleapis.com/* https://js.intercomcdn.com/ https://widget.intercom.io; object-src 'self'",
  "permissions": [
    "management",
    "webRequest",
    "webRequestBlocking",
    "storage",
    "gcm",
    "tabs",
    "notifications",
    "*://*.google.com/",
    "https://inbox.google.com/",
    "http://*/*",
    "https://*/*",
    "http://localhost/*"
  ],
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "browser_action": {
    "default_icon": "img/ES_envelope_button.png",
    "default_popup": "popup.html"
  },
  "name": "EmailStationery.com",
  "description": "Emailstationery.com",
  "icons": {
    "16": "img/escom_16.png",
    "48": "img/escom_48.png",
    "128": "img/ES_icon_128.png"
  },
  "short_name": "Es.com",
  "browser_specific_settings": {
    "gecko": {
      "id": "emailStationeryFFToolbar@emailStationeryFFToolbar"
    }
  }
}