Examine source code of PDF Annotator

{
  "manifest_version": 2,
  "name": "PDF Annotator",
  "version": "1.0",
  "description": "Open, highlight, and annotate PDF files.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{25619e5d-ec2c-4304-8a9e-236cd69d0e2d}"
    }
  }
}