Examine source code of ExpandComments

{
  "manifest_version": 2,
  "name": "ExpandComments",
  "version": "1.7",
  "description": "Expand comments in 9Gag, Investing.com/de, Hofer-Reisen by pressing ALT+Y",
  "icons": {
    "48": "icons/bookmark-it.png",
    "96": "icons/bookmark-it@2x.png"
  },
  "permissions": [
    "activeTab"
  ],
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Alt+Y"
      }
    }
  },
  "browser_action": {
    "default_icon": "icons/star-empty-38.png",
    "default_title": "Expand_Comments"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}