Examine source code of XBookSync

{
  "manifest_version" : 2 ,
  "name" : "XBookSync",
  "description" : "Bookmark sync utility for Chrome and Firefox",
  "version" : "0.5.2",
  "icons" : {
    "16" : "icons/16.png",
    "32" : "icons/32.png",
    "48" : "icons/48.png",
    "128" : "icons/128.png"
  },
  "permissions" : [
    "storage" ,
    "bookmarks" ,
    "alarms" ,
    "notifications" ,
    "https://github.com/*" ,
    "https://api.github.com/*" 
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "developers@xbooksync.org",
      "data_collection_permissions": {
        "required": [
          "bookmarksInfo"
        ],
        "optional": []
      }
    }
  },
  "background" : {
    "scripts" : [
      "background.js" 
    ]
  },
  "browser_action" : {
    "default_title" : "XBookSync",
    "default_popup" : "popup.html"
  },
  "options_ui" : {
    "open_in_tab": true,
    "browser_style": true,
    "page": "options.html" 
  }
}