go.tools/dashboard/app: update CL threads with perf notifications
go.tools/dashboard/app: update CL threads with perf notifications

LGTM=dvyukov
R=dvyukov
CC=golang-codereviews, rsc
https://golang.org/cl/135460043

evandbrown/build,evandbrown/build,proppy/build,golang/build,proppy/build,proppy/build,golang/build,golang/build,evandbrown/build,proppy/build,golang/build