Examine source code of Timer Safe

{
  "manifest_version": 2,
  "name": "Timer Safe",
  "version": "9.19.15",
  "description": "Built-in Pomodoro timer to boost your daily productivity.",
  "browser_specific_settings": {
    "gecko": {
      "id": "link-tool-feed@quickext.example",
      "strict_min_version": "101.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "tabs",
    "sessions",
    "storage",
    "unlimitedStorage",
    "notifications",
    "alarms",
    "<all_urls>"
  ],
  "browser_action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "64": "icons/icon-64.png",
      "128": "icons/icon-128.png"
    },
    "default_title": "Timer Safe",
    "default_popup": "popup/popup.html"
  },
  "background": {
    "scripts": [
      "background/background.js"
    ]
  },
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "128": "icons/icon-128.png"
  },
  "commands": {
    "restore-last-tab": {
      "suggested_key": {
        "default": "Ctrl+Shift+T"
      },
      "description": "Restore last closed tab"
    },
    "save-all-tabs": {
      "suggested_key": {
        "default": "Ctrl+Shift+S"
      },
      "description": "Save all open tabs"
    },
    "open-popup": {
      "suggested_key": {
        "default": "Ctrl+Shift+M"
      },
      "description": "Open TabMaster Pro"
    }
  }
}