Renderer process hangs whenever a renderer closes an audio stream (which happens on youtube at the end of pre-roll ads). Problem also reproduces when navigating to a different page while <audio> is playing.

The problem is that after base::SyncSocket::Shutdown() doesn't work for SyncSocket handles that are passed from one process to another. It looks like the problem is in FDIO: it unwraps FDs created with socketpair() as PA_FDIO_PIPE. As result fdio_create_fd() handles it as a pipe and shutdown() is not supported for pipes.

Another problem is that media::AudioDeviceThread ignores errors from Shutdown().

Landed https://fuchsia-review.googlesource.com/c/zircon/+/179804 to address this, so we should verify that shutdown() works as expected in Chromium, once that rolls into the SDK tomorrow.

The NextAction date has arrived: 2018-09-06

With the current build of fuchsia and webrunner renderer no longer hangs, but it also fails to play audio frequently. Particularly on youtube audio plays on pre-roll add, but not for video itself. I'm not sure if that's related to the FDIO bug. 

Re #7: OK; sounds like something else has regressed. Closing this out as Fixed, let's file a separate bug for the new issue (or re-open this one if it does look to be related to socketpair() shutdown()).