Examine source code of tabSessions

{
  "manifest_version": 2,
  "name": "tabSessions",
  "version": "1.1resigned1",
  "description": "Adds a tab-session manager to Firefox",
  "homepage_url": "https://tabsessions.info",
  "icons": {
    "48": "icons/bookmark-it.png",
    "96": "icons/bookmark-it@2x.png"
  },
  "permissions": [
    "<all_urls>",
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_icon": "icons/star-empty-38.png",
    "default_title": "tabSessions",
    "default_popup": "popup/session_manager.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7e0ad6fa-e16a-4753-a2ce-4a83bd37b1c0}"
    }
  }
}