Examine source code of Drum-Screenshare

{
  "name": "Drum Screenshare",
  "short_name": "Drum",
  "author": "thisisdrum.com",
  "version": "1.0.0.21resigned1",
  "manifest_version": 2,
  "minimum_chrome_version": "50",
  "description": "This extension implements the screen sharing functionality used by Drum meetings",
  "homepage_url": "https://thisisdrum.com/",
  "background": {
    "scripts": [
      "background-script.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "js": [
        "content-script.js"
      ],
      "run_at": "document_end",
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "all_frames": true
    }
  ],
  "icons": {
    "14": "icons/icon14.png",
    "16": "icons/icon16.png",
    "20": "icons/icon20.png",
    "24": "icons/icon24.png",
    "25": "icons/icon25.png",
    "30": "icons/icon30.png",
    "32": "icons/icon32.png",
    "40": "icons/icon40.png",
    "48": "icons/icon48.png",
    "64": "icons/icon64.png",
    "128": "icons/icon128.png",
    "256": "icons/icon256.png"
  },
  "permissions": [
    "desktopCapture",
    "tabs",
    "http://*/*",
    "https://*/*"
  ],
  "web_accessible_resources": [
    "icons/icon*.png"
  ],
  "externally_connectable": {
    "matches": [
      "http://localhost:8080/*",
      "http://*.thisisdrum.com/*",
      "https://*.thisisdrum.com/*",
      "http://*.blinkmeetings.com/*",
      "https://*.blinkmeetings.com/*",
      "http://*.vhost.work/*",
      "https://*.vhost.work/*",
      "http://*.vhost.work/*",
      "https://*.vhost.work/*",
      "http://*.azure.vhost.work/*",
      "https://*.azure.vhost.work/*",
      "http://meeting.powwownow.co.uk/*",
      "https://meeting.powwownow.co.uk/*"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0a1562bf-e779-48dd-8f88-405c37004c44}"
    }
  }
}