Chrome Dev here. Still trying, and currently failing, to ship App Container (Low Box Token) for renderer processes.

We strongly suspect AV is tampering with renderer process startup causing our attempts to set the low box token to fail (the token manipulation has to occur while the process is suspended, and we suspect AV is injecting threads at this point).

Either that or AV is just crashing the process because it does not expect its calls to fail inside the sandbox.

Very frustrating. Glad jschuh has come out and said what we all believe.