DevTools: Update tracing process filters when process is ready.

Drive-by: Fix a failing DCHECK on Pid() invoked on a non-ready process.

BUG=848398,849887

Change-Id: I1df89b5027ec5ed85235566427dd767ade092fa0
Reviewed-on: https://chromium-review.googlesource.com/1128055
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573099}
2 files changed