Examine source code of Highlighter Extension

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "manifest_version": 2,
  "name": "Highlighter Extension",
  "version": "1.5.5",
  "permissions": [
    "storage",
    "activeTab",
    "scripting",
    "contextMenus"
  ],
  "icons": {
    "16": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "action": {
    "default_title": "Highlight Text or View Highlights",
    "default_icon": "icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{aaa20613-b07e-46c8-846a-80326f574cf4}"
    }
  }
}