Examine source code of Proposeful.com

{
  "name": "__MSG_extensionName__",
  "description": "__MSG_extensionDescription__",
  "version": "1.0.2",
  "manifest_version": 2,
  "default_locale": "en",
  "icons": {
    "16": "img/logo-16.png",
    "32": "img/logo-32.png",
    "48": "img/logo-48.png",
    "96": "img/logo-96.png",
    "128": "img/logo-128.png"
  },
  "web_accessible_resources": [
    "img/icon-close.png",
    "img/icon-resize.png",
    "img/icon-swap.png",
    "img/loading.svg",
    "img/logo-text.png",
    "img/logo.png",
    "error.html"
  ],
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "js/browser-polyfill.min.js",
        "js/proposeful-modal.js"
      ]
    }
  ],
  "browser_action": {
    "default_title": "Proposeful",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "img/logo-16.png",
      "32": "img/logo-32.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{02da25a5-5c01-4a90-b5ec-0271e653d9c7}"
    }
  }
}