Examine source code of Go Focus Self

{
  "name": "__MSG_extensionName__",
  "author": "Terry",
  "version": "0.2.1",
  "description": "__MSG_extensionDescription__",
  "manifest_version": 2,
  "default_locale": "en",
  "icons": {
    "24": "icon_24.png",
    "48": "icon_48.png",
    "96": "icon_96.png"
  },
  "commands": {
    "focus-text-box": {
      "suggested_key": {
        "default": "Ctrl+Shift+1"
      },
      "description": "Focus the text box on the current webpage nearest the center of the screen."
    }
  },
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  }
}