Examine source code of Tab ReTitle

{
  "manifest_version": 2,
  "name": "Tab ReTitle",
  "short_name": "ReTitle",
  "description": "Change tab titles easily!",
  "version": "1.5.2",
  "author": "Lazyuki",
  "homepage_url": "https://github.com/Lazyuki/ReTitle",
  "browser_action": {
    "default_icon": "./images/icon256.png",
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "./images/icon16.png",
    "32": "./images/icon32.png",
    "64": "./images/icon64.png",
    "128": "./images/icon128.png",
    "256": "./images/icon256.png"
  },
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "options_ui": {
    "page": "options.html",
    "chrome_style": true
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Alt+Shift+X",
        "mac": "Alt+Shift+X",
        "linux": "Alt+Shift+X"
      },
      "description": "Set new title"
    }
  },
  "permissions": [
    "activeTab",
    "tabs",
    "storage",
    "<all_urls>",
    "contextMenus",
    "bookmarks"
  ]
}