Examine source code of Save on Later

{
  "manifest_version": 2,
  "name": "Save on Later",
  "version": "1.0",
  "description": "Quickly save the current webpage on Later",
  "icons": {
    "32": "later_32.png",
    "48": "later_48.png",
    "128": "later_128.png"
  },
  "permissions": [
    "tabs"
  ],
  "browser_action": {
    "default_title": "Save on Later",
    "default_icon": "later_128.png"
  },
  "background": {
    "scripts": [
      "index.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{37f246ff-98f9-4005-a429-df207465ea78}"
    }
  }
}