Doubletick - Email tracking for Gmail

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Doubletick - Email tracking for Gmail",
  "description": "Get whatsapp like double checkmarks when someone reads your email",
  "version": "3.3.1",
  "icons": {
    "16": "dt-16.png",
    "48": "dt-48.png",
    "128": "dt-128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "dt-16.png",
      "24": "dt-24.png",
      "32": "dt-32.png"
    },
    "default_title": "Doubletick - Email tracking for Gmail",
    "default_popup": "index.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*"
      ],
      "run_at": "document_end",
      "all_frames": false,
      "js": [
        "inboxsdk.js",
        "content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "enabled.svg",
    "disabled.svg",
    "un-read.svg",
    "logo.png"
  ],
  "permissions": [
    "storage",
    "notifications",
    "webRequest",
    "webRequestBlocking",
    "https://mail.google.com/",
    "https://*.getdoubletick.com/*",
    "*://*.googleusercontent.com/*"
  ],
  "externally_connectable": {
    "matches": [
      "https://*.getdoubletick.com/*"
    ]
  },
  "manifest_version": 2
}