Examine source code of Crate

{
  "manifest_version": 2,
  "name": "Crate",
  "description": "Save content to your Crate account.",
  "version": "0.2.0",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "author": "Crate, Inc.",
  "permissions": [
    "storage",
    "activeTab",
    "identity"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "engineering@crate.co"
    }
  },
  "background": {
    "persistent": true,
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Crate",
    "default_popup": "popup.html"
  }
}