Examine source code of Bigger URL bar

{
  "name": "Bigger URL bar",
  "description": "Bigger URL bar with multiple lines by @h43z. Press CTRL+Shift+L to open URL bar, hitting ESC or making it loose focus will hide it again. Extension code only injects itself when needed.",
  "manifest_version": 2,
  "version": "1.3",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "activeTab"
  ],
  "commands": {
    "toggle-feature": {
      "suggested_key": {
        "default": "Ctrl+Shift+L"
      },
      "description": "Open URL bar"
    }
  }
}