Examine source code of Mouse Tooltip Translator - PDF & Youtube dual subs

{
  "manifest_version": 2,
  "version": "0.1.244",
  "name": "__MSG_appName__",
  "description": "__MSG_appDesc__",
  "default_locale": "en",
  "icons": {
    "16": "icons/icon_16.png",
    "32": "icons/icon_32.png",
    "48": "icons/icon_48.png",
    "128": "icons/icon_128.png"
  },
  "content_security_policy": "script-src 'self' 'wasm-unsafe-eval' ;  object-src 'none'",
  "permissions": [
    "storage",
    "tabs",
    "scripting",
    "contextMenus",
    "search",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "web_accessible_resources": [
    "pdfjs/web/viewer.html",
    "ocr.html",
    "opencvHandler.html",
    "videoHandler.js",
    "googleDocInject.js",
    "subtitle.js",
    "offscreen.js",
    "popup.html"
  ],
  "commands": {
    "copy-translated-text": {
      "suggested_key": {
        "default": "Ctrl+Shift+6"
      },
      "description": "Copy Translated Text"
    },
    "copy-source-text": {
      "suggested_key": {
        "default": "Ctrl+Shift+7"
      },
      "description": "Copy Source Text"
    }
  },
  "omnibox": {
    "keyword": "/"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "mouse.tooltip.translator@gmail.com"
    }
  },
  "content_scripts": [
    {
      "js": [
        "contentScript.js"
      ],
      "css": [
        "tippy.css"
      ],
      "run_at": "document_start",
      "all_frames": true,
      "matches": [
        "<all_urls>"
      ],
      "match_about_blank": true
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Mouse Tooltip Translator",
    "default_popup": "popup.html"
  },
  "options_ui": {
    "page": "popup.html"
  }
}