See https://cs.chromium.org/chromium/src/content/browser/gpu/gpu_process_host.cc?q=gpu_process_host&dr=CSs&l=593, where apparently a new connection filter accrues to the browser each time we spawn a GPU process. The number of spawned GPU processes isn't bounded to my knowledge, as we re-spin the process on crash.
I don't know whether other process types are handled similarly, maybe this is worth an audit - or some form of introspection would be nice on Connectors?