Mysterious "ITaskHost" mention in BotR threading chapter

[sgbench]

I was just reading the threading chapter of the Book of the Runtime, and in the Synchronization: Native section, I came across the following:

The ITaskHost API allows a host to override many aspects of managed threading, including thread creation, destruction, and synchronization. The ability of a host to override native synchronization means that VM code can generally not use native synchronization primitives (Critical Sections, Mutexes, Events, etc.) directly, but rather must use the VM's wrappers over these.

I've never heard of an "ITaskHost API" (or any API for that matter) that allows a host to override managed threading behavior as described here. Both a Google search and a GitHub search of dotnet/runtime yielded nothing interesting, aside from references to this BotR chapter and Microsoft.Build.Framework.ITaskHost, which definitely isn't what this passage is referring to.

Can anyone shed some light on this? Was the author potentially referring to IHostTask or IHostTaskManager from the old .NET Framework unamanged hosting interfaces? If so, perhaps this section of the chapter should be corrected and/or clarified.