Examine source code of Open All Links

{
  "manifest_version": 2,
  "name": "Open All Links",
  "version": "1.0",
  "description": "Opens all links from the page in new tabs.",
  "browser_action": {
    "default_icon": {
      "64": "icon64.png",
      "128": "icon128.png"
    },
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{4d4d870d-55d9-4184-a34c-8bd8874d5698}",
      "strict_min_version": "109.0"
    }
  },
  "icons": {
    "64": "icon64.png",
    "128": "icon128.png"
  }
}