Examine source code of Offline Email Reader

{
  "manifest_version": 2,
  "name": "Offline Email Reader",
  "version": "1.0",
  "description": "A Mozilla addon to create and manage offline email reading list.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_icon": {
      "48": "icon.png"
    },
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{2583fb8c-000a-45a7-9f3e-199e5e8ff388}"
    }
  }
}