Examine source code of productivity utility

{
  "manifest_version": 2,
  "name": "productivity utility",
  "description": "This extension is a utility for the productivity app.",
  "permissions": [
    "nativeMessaging",
    "tabs"
  ],
  "version": "1.5",
  "icons": {
    "16": "/images/icon16.png",
    "48": "/images/icon48.png",
    "128": "/images/icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    },
    {
      "matches": [
        "https://www.youtube.com/*"
      ],
      "css": [
        "video_layout.css"
      ],
      "js": [
        "youtube_curate.js"
      ],
      "run_at": "document_start"
    },
    {
      "matches": [
        "https://www.facebook.com/*"
      ],
      "js": [
        "facebook_curate.js"
      ],
      "run_at": "document_start"
    },
    {
      "matches": [
        "https://www.instagram.com/*"
      ],
      "js": [
        "instagram_curate.js"
      ],
      "run_at": "document_start"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "web_accessible_resources": [
    "blocked_page/blocked.html",
    "blocked_page/blocked.css",
    "blocked_page/landscape.jpg",
    "blocked_vid/distraction.png"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{251e9a9f-1942-466b-9915-1af164d04b9a}"
    }
  }
}