Examine source code of Tabouleh

{
  "name": "Tabouleh",
  "description": "Breeze through your most recent tabs.",
  "version": "1.4.0",
  "icons": {
    "1024": "icon.png"
  },
  "manifest_version": 2,
  "browser_action": {
    "default_popup": "popup.html"
  },
  "background": {
    "page": "background.html",
    "persistent": false
  },
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "permissions": [
    "storage",
    "tabs",
    "activeTab"
  ],
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+1",
        "mac": "Command+Shift+1"
      }
    },
    "switch-last-tab": {
      "suggested_key": {
        "default": "Ctrl+Shift+2",
        "mac": "Command+Shift+2"
      },
      "description": "Instantly switch to the last active tab."
    }
  }
}