Examine source code of Tab Manager JJM

{
  "manifest_version": 2,
  "name": "Tab Manager",
  "version": "1",
  "description": "Assist user to organize and ease the operation of multiple windows and tabs with a variety of useful features.",
  "icons": {
    "48": "icons/tab-48.png",
    "96": "icons/tab-96.png"
  },
  "permissions": [
    "tabs",
    "storage",
    "activeTab",
    "contextMenus",
    "<all_urls>",
    "cookies",
    "contextualIdentities"
  ],
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": true
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content/content.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "icons/tab-32.png",
    "default_title": "Tab Manager",
    "default_popup": "popup/index.html"
  },
  "background": {
    "scripts": [
      "background/background.js"
    ]
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+Space",
        "mac": "MacCtrl+Shift+Space"
      },
      "description": "Open Tab Manager, with focus on the search bar"
    },
    "open-tab-focus-current": {
      "suggested_key": {
        "default": "Ctrl+Shift+X",
        "mac": "MacCtrl+Shift+X"
      },
      "description": "Open Tab Manager, with focus on the current tab"
    },
    "last-used-tab": {
      "suggested_key": {
        "default": "Ctrl+Shift+L",
        "mac": "MacCtrl+Shift+L"
      },
      "description": "Open last used tab"
    },
    "last-used-window": {
      "suggested_key": {
        "default": "Ctrl+Shift+0",
        "mac": "MacCtrl+Shift+0"
      },
      "description": "Open last used window"
    }
  },
  "applications": {
    "gecko": {
      "id": "tabmanager@gmail.com",
      "strict_min_version": "59.0"
    }
  }
}