Window service has two modes (and two flags): called 'mus' and 'mash'. In the 'mus' mode, the GpuProcessHost should be (and is) created, because browser is still responsible for managing the display compositor (i.e. the browser is the viz host). In 'mash' mode, the GpuProcessHost should not be (and is not) created, because the window-service is the viz-host.

Are you seeing a different behaviour? Because we have tests running on the bots that would (hopefully!) break if this wasn't happening correctly.

With mash, the following test breaks indicating we constructed a GpuProcessHost EncryptedMediaTestExperimentalCdmInterface.CdmProxy. Here is the log with the failure: https://build.chromium.org/deprecated/tryserver.chromium.chromiumos/builders/linux-chromeos-rel/builds/66601/steps/mash_browser_tests%20(with%20patch)/logs/EncryptedMediaTestExperimentalCdmInterface.CdmProxy

We tried to de-reference the DiscardableSharedMemoryManager from GpuProcessHost::Init, which is not initialized for mash.