Examine source code of OP Downloader

{
  "manifest_version": 2,
  "name": "OP Downloader",
  "version": "1.2",
  "description": "Let you preview/download files from GitLab in the FASTEST way.",
  "icons": {
    "48": "icons/icon.png",
    "96": "icons/icon96.png",
    "128": "icons/icon128.png"
  },
  "author": "PY Chen & Omega Feng",
  "background": {
    "scripts": [
      "background.js",
      "extensionToMIME.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_end",
      "css": [
        "download-button.css"
      ],
      "js": [
        "download-button.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "icons/*",
    "imgs/*"
  ],
  "permissions": [
    "tabs",
    "downloads",
    "https://github.com/*",
    "https://raw.githubusercontent.com/*"
  ]
}