Examine source code of Tabs Closer

{
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "48": "icon.png"
    },
    "default_title": "__MSG_close_tabs__"
  },
  "commands": {
    "close": {
      "suggested_key": {
        "default": "Ctrl+Shift+L"
      },
      "description": "Close tabs"
    }
  },
  "default_locale": "en",
  "description": "__MSG_description__",
  "icons": {
    "48": "icon.png"
  },
  "manifest_version": 2,
  "name": "__MSG_name__",
  "permissions": [
    "contextMenus",
    "tabs"
  ],
  "version": "0.0.1"
}