Examine source code of Fastnote

{
  "manifest_version": 2,
  "name": "Fastnote",
  "version": "1.2resigned1",
  "description": "Allows the user to make quick notes by clicking a button and entering text into the resulting popup. The notes are saved in storage. See https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Examples#quicknote",
  "icons": {
    "48": "icons/quicknote-48.png"
  },
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_icon": {
      "32": "icons/quicknote-32.png"
    },
    "default_title": "fastnote",
    "default_popup": "popup/quicknote.html"
  },
  "applications": {
    "gecko": {
      "id": "fastnote-example@mytest.org"
    }
  }
}