You can get the "root" Chrome process using WMI. The Win32_Process
] class has a property called ParentProcessId.
In the case where Chrome is launched by the user through launching a Chrome shortcut from Explorer, get the ProcessId of "explorer" and then get the Win32_Process instances for "chrome". The root process is the one that has a ParentProcessId matching the ProcessId of "explorer".
If Chrome is being launched by another application, like clicking a link in Outlook, or from some other application you've written, the ProcessId of the parent is going to be the one that launched Chrome, not the one for "explorer".