Examine source code of Switch To Previous Active Tab & Reload All Tabs

{
  "manifest_version": 2,
  "name": "Switch To Previous Active Tab",
  "description": "Flips to the last accessed tab in the same window, or in any window.",
  "version": "2.6.1",
  "browser_specific_settings": {
    "gecko": {
      "id": "{f01b6ea5-5910-4359-afee-9f0de052c7a1}",
      "strict_min_version": "139.0"
    }
  },
  "developer": {
    "name": "Jefferson \"jscher2000\" Scher",
    "url": "https://github.com/jscher2000/switch-to-previous-active-tab"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": "icons/nolasttab-32.png",
    "default_title": "Change tabs to enable"
  },
  "permissions": [
    "menus",
    "tabs",
    "storage",
    "contextualIdentities",
    "tabGroups"
  ],
  "icons": {
    "16": "icons/lasttab-16.png",
    "32": "icons/lasttab-32.png",
    "64": "icons/previousactivetab.png"
  },
  "commands": {
    "previous-tab": {
      "suggested_key": {
        "default": "Alt+Shift+Left",
        "mac": "MacCtrl+Shift+Left"
      },
      "description": "Switch to previous active tab (same window)"
    },
    "previous-tab-global": {
      "description": "Switch to previous active tab in any window"
    },
    "show-list": {
      "suggested_key": {
        "default": "Ctrl+Shift+Down",
        "mac": "MacCtrl+Shift+Down"
      },
      "description": "Open list drop-down (select window or global in the Options)"
    },
    "activate-tab-1": {
      "description": "Go to 1st tab (skip pinned, hidden, unloaded, per options)"
    },
    "activate-tab-2": {
      "description": "Go to 2nd tab (skip pinned, hidden, unloaded, per options)"
    },
    "activate-tab-3": {
      "description": "Go to 3rd tab (skip pinned, hidden, unloaded, per options)"
    },
    "activate-tab-4": {
      "description": "Go to 4th tab (skip pinned, hidden, unloaded, per options)"
    },
    "activate-tab-5": {
      "description": "Go to 5th tab (skip pinned, hidden, unloaded, per options)"
    },
    "activate-tab-6": {
      "description": "Go to 6th tab (skip pinned, hidden, unloaded, per options)"
    },
    "activate-tab-7": {
      "description": "Go to 7th tab (skip pinned, hidden, unloaded, per options)"
    },
    "activate-tab-8": {
      "description": "Go to 8th tab (skip pinned, hidden, unloaded, per options)"
    },
    "activate-tab-9": {
      "description": "Go to 9th tab (skip pinned, hidden, unloaded, per options)"
    }
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  }
}