Examine source code of Pubmed

{
  "manifest_version": 2,
  "name": "Pubmed",
  "version": "1.0",
  "description": "Add a context menu for searching pubmed article",
  "icons": {
    "48": "icons/48x48.png"
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/48x48.png",
      "96": "icons/96x96.png"
    }
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}