Reland of DevTools: Stop collecting async stacks while profiling. (https://codereview.chromium.org/257453005/)

The revert did not fix the flakiness.

Original: r172762 (https://codereview.chromium.org/257453005/)
Revert: r173072 (https://codereview.chromium.org/264743005/)

TBR=pfeldman@chromium.org,sergeyv@chromium.org,yurys@chromium.org,aandrey@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=367135

Review URL: https://codereview.chromium.org/264793003

git-svn-id: svn://svn.chromium.org/blink/trunk@173076 bbb929c8-8fbe-4397-9dbb-9b2b20218538