Examine source code of Tab Master

{
  "manifest_version": 2,
  "name": "Tab Master",
  "version": "1.1.0",
  "description": "Navigate freely. Tab Master provides easy and intuitive way to navigate trough tabs and history",
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "background": {
    "scripts": [
      "browser-polyfill.js",
      "background/index.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "browser-polyfill.js",
        "modal/index.js"
      ]
    }
  ],
  "permissions": [
    "<all_urls>",
    "tabs",
    "history",
    "storage"
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "commands": {
    "open-tab-master": {
      "suggested_key": {
        "mac": "Command+Shift+K",
        "chromeos": "Ctrl+Shift+K",
        "windows": "Ctrl+Shift+K",
        "linux": "Ctrl+Shift+K"
      },
      "description": "Open Tab Master Extension"
    }
  },
  "browser_action": {
    "default_popup": "popup/index.html"
  },
  "options_ui": {
    "page": "popup/index.html"
  },
  "web_accessible_resources": [
    "/images/icon16.png",
    "/fonts/KumbhSans-Bold.ttf",
    "/fonts/KumbhSans-Regular.ttf"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{4d18ba5c-53a5-4c14-b3ad-753bc5d8a70b}",
      "strict_min_version": "42.0"
    }
  }
}