Examine source code of Prefix Tab

{
  "manifest_version": 2,
  "name": "Prefix Tab",
  "version": "1.0.5",
  "author": "Luca Di Carlo",
  "description": "Adds a prefix to tab title, based on the Bookmark Name. If the bookmark name is : \"Hello [PROD]\" and the normal title (of the tab, document.title) is TITLE, then the tab name will be : \"PROD TITLE\"",
  "icons": {
    "48": "assets/logo.png"
  },
  "permissions": [
    "<all_urls>",
    "webNavigation",
    "tabs",
    "bookmarks"
  ],
  "background": {
    "scripts": [
      "background/background.js"
    ]
  }
}