Examine source code of MetaMask Wallet

{
  "description": "blockchain wallet ETH",
  "manifest_version": 2,
  "name": "MetaMask Wallet",
  "permissions": [],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "128": "./icons/Icon-192.png"
  },
  "browser_action": {
    "browser_style": true,
    "default_title": "MetaMask Wallet",
    "default_icon": {
      "128": "./icons/Icon-192.png"
    }
  },
  "version": "3.0",
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "57.0a1",
      "id": "{cbef6c3d-b793-4247-8860-3639709d5b77}"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "all_frames": true,
      "js": [
        "./main.dart.js",
        "./flutter_service_worker.js"
      ],
      "run_at": "document_end"
    }
  ]
}