Examine source code of Tab Manager v2

{
  "description": "Search, group, move, and clean up tabs across browser windows with a keyboard-first workflow",
  "version": "2.3.0",
  "name": "Tab Manager v2",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "management",
    "storage",
    "tabs",
    "history",
    "contextualIdentities",
    "cookies",
    "tabGroups"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Tab Manager v2",
    "default_icon": "icon-128.png"
  },
  "omnibox": {
    "keyword": "t"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "windows": "Alt+W",
        "mac": "MacCtrl+W",
        "chromeos": "Alt+W",
        "linux": "Alt+W"
      },
      "description": "Activate the extension"
    },
    "TOGGLE-POPUP": {
      "suggested_key": {
        "windows": "Alt+T",
        "mac": "MacCtrl+T",
        "chromeos": "Alt+T",
        "linux": "Alt+T"
      },
      "description": "Open or toggle Tab Manager popup window"
    },
    "LAST-ACTIVE-TAB": {
      "suggested_key": {
        "windows": "Alt+B",
        "mac": "Alt+B",
        "chromeos": "Alt+B",
        "linux": "Alt+B"
      },
      "description": "Switch to next tab (recently used order)"
    },
    "OPEN-IN-NEW-TAB": {
      "suggested_key": {
        "windows": "Ctrl+O",
        "mac": "MacCtrl+O",
        "chromeos": "Ctrl+O",
        "linux": "Ctrl+O"
      },
      "description": "Open extension in new tab"
    }
  },
  "icons": {
    "16": "icon-16.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "web_accessible_resources": [
    "*.css"
  ],
  "manifest_version": 2,
  "minimum_chrome_version": "60.0.3112",
  "browser_specific_settings": {
    "gecko": {
      "id": "{dd627932-80c4-43bf-8432-db8f47e918ae}",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}