Examine source code of Keplr

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Keplr",
  "short_name": "Keplr Tab Manager+",
  "version": "5.3.0",
  "manifest_version": 2,
  "offline_enabled": true,
  "description": "Keplr :Quickly find open tabs, see all windows in one view, find duplicates and limit tabs per window. The best Tab Manager for Chrome.",
  "author": "Keplr",
  "icons": {
    "128": "icon_128.png"
  },
  "permissions": [
    "tabs",
    "contextMenus",
    "storage"
  ],
  "optional_permissions": [
    "system.display"
  ],
  "incognito": "spanning",
  "background": {
    "scripts": [
      "vendor/babel-polyfill.js",
      "vendor/browser-polyfill.min.js",
      "outlib/background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_icon": {
      "128": "icon_128.png"
    }
  },
  "options_ui": {
    "page": "Tab1.html"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+M",
        "windows": "Ctrl+Shift+M",
        "mac": "Command+Shift+M"
      }
    },
    "switch_to_previous_active_tab": {
      "suggested_key": {
        "default": "Ctrl+Shift+Space",
        "windows": "Ctrl+Shift+Space",
        "mac": "Command+Shift+Space"
      },
      "description": "Switches to previously active tab"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{13136230-8576-4f1d-be14-e707b0c6f39f}"
    }
  }
}