Examine source code of Merge PDF files.

{
  "manifest_version": 2,
  "name": "ME",
  "version": "1",
  "description": "Merge PDF files.",
  "browser_action": {
    "default_icon": "icon.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{6f8e373f-2a11-49f6-b442-9f4d23c53160}"
    }
  }
}