Examine source code of Shift Tab

{
  "manifest_version": 2,
  "name": "Shift tab",
  "version": "1.1",
  "description": "Go to next tab using Alt + l. Go to previous tab using Alt + h. Move current tab to the left with Alt + H. Move current tab to...",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "commands": {
    "switch_to_previous_tab": {
      "suggested_key": {
        "default": "Alt+H"
      },
      "description": "Go to previous using Alt + l"
    },
    "switch_to_next_tab": {
      "suggested_key": {
        "default": "Alt+L"
      },
      "description": "Go to next tab using Alt + h"
    },
    "move_tab_left": {
      "suggested_key": {
        "default": "Alt+Shift+H"
      },
      "description": "Move the current tab to the left"
    },
    "move_tab_right": {
      "suggested_key": {
        "default": "Alt+Shift+L"
      },
      "description": "Move the current tab to the right"
    }
  },
  "icons": {
    "48": "icons/icon48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{8872db2d-f45b-4ee3-a150-d9caefad881e}"
    }
  }
}