Examine source code of Moris Timer

{
  "manifest_version": 2,
  "name": "Moris Timer",
  "version": "2.65",
  "default_locale": "en",
  "description": "__MSG_extensionDescription__",
  "permissions": [
    "storage",
    "notifications"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "web_accessible_resources": [
    "sound.mp3",
    "bell.mp3",
    "digital.mp3",
    "gentle.mp3"
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "moris-timer@digitour.de"
    }
  }
}