Examine source code of NES Emulator

{
  "manifest_version": 2,
  "name": "NES Emulator",
  "short_name": "NES Emulator",
  "description": "Relive the nostalgia of classic NES games directly in your browser!",
  "version": "1.0",
  "author": "Hunkie Peanut",
  "permissions": [
    "storage",
    "<all_urls>",
    "declarativeNetRequestWithHostAccess"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ],
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "web_accessible_resources": [
    "icons/*.png",
    "styles/*.css",
    "welcome.html",
    "fullscreen.html",
    "pascoli.html"
  ],
  "content_security_policy": "script-src 'self'; object-src 'self';",
  "browser_specific_settings": {
    "gecko": {
      "id": "{1b13f7d0-640b-418e-8414-b65bcb131a9a}"
    }
  }
}