Examine source code of Time Tracker v2

{
  "name": "Time Tracker",
  "description": "Calculates how many seconds is left for the day",
  "version": "1.0",
  "manifest_version": 2,
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+F",
        "mac": "MacCtrl+Shift+F"
      },
      "description": "Calculates how many seconds is left for the day"
    }
  },
  "permissions": [
    "<all_urls>"
  ],
  "chrome_url_overrides": {
    "newtab": "newtab.html"
  }
}