I was looking to enforce only sending valid FrameSinkIds, LocalSurfaceIds, and SurfaceIds, via classic IPC. (Mojo already enforces this)

This found a bug via mash_browsertests where CrossProcessFrameConnector::SetView is trying to send invalid FrameSinkIds.

The following tests fail:

WebviewLoginTest.AllowNewUser
EnterpriseEnrollmentTest.TestAuthCodeGetsProperlyReceivedFromGaia
PowerPolicyLoginScreenBrowserTest.SetDevicePolicy
EnterpriseEnrollmentTest.TestActiveDirectoryEnrollment_Success