Examine source code of Route Mark

{
  "name": "Route Mark",
  "version": "1.0",
  "description": "Firefox extension for makking bookmarks easier to access",
  "permissions": [
    "storage",
    "tabs",
    "unlimitedStorage"
  ],
  "browser_action": {
    "default_title": "Google Mail",
    "default_popup": "pop.html"
  },
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "manifest_version": 2
}