Examine source code of Highlight keywords on web

{
  "manifest_version": 2,
  "name": "Keyword Highlighter",
  "version": "3.7",
  "description": "Highlight keywords on web pages with notes and comments",
  "permissions": [
    "storage",
    "tabs",
    "<all_urls>"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "logo16.png",
      "32": "logo32.png",
      "48": "logo48.png",
      "128": "logo128.png"
    }
  },
  "icons": {
    "16": "logo16.png",
    "32": "logo32.png",
    "48": "logo48.png",
    "128": "logo128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "highlight.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "web_accessible_resources": [
    "lang_ru.json",
    "lang_en.json",
    "lang_es.json"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "keyword-highlighter@bummer"
    }
  }
}