Examine source code of Tablet Toolbar

{
  "description": "A few actions to ease use with firefox on touch screen devices (switching and closing tabs and opening links in new tab)",
  "manifest_version": 2,
  "name": "Tablet Toolbar",
  "version": "1.1resigned1",
  "homepage_url": "http://no-homepage-yet.com/",
  "icons": {
    "48": "icons/app.svg"
  },
  "permissions": [
    "tabs",
    "storage",
    "notifications",
    "webNavigation"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/32.png",
    "default_title": "In Page Toolbar"
  },
  "content_scripts": [
    {
      "js": [
        "contentscript.js"
      ],
      "run_at": "document_end",
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "web_accessible_resources": [
    "toolbar/ui.html"
  ],
  "applications": {
    "gecko": {
      "id": "TabletToolbar@google.com",
      "strict_min_version": "48.0"
    }
  }
}