Revert "trace viewer: Remove the heading from the spacing track"
Revert "trace viewer: Remove the heading from the spacing track"

This reverts commit 64ae144a61f13e89486f65a15033c130c1342ca3.

TBR=petrcermak@chromium.org
BUG=catapult:#2100

Review URL: https://codereview.chromium.org/1767153002 .

sahiljain/catapult,benschmaus/catapult,sahiljain/catapult,catapult-project/catapult,benschmaus/catapult,sahiljain/catapult,catapult-project/catapult,benschmaus/catapult,sahiljain/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,sahiljain/catapult,benschmaus/catapult,catapult-project/catapult-csm,catapult-project/catapult,benschmaus/catapult,catapult-project/catapult,catapult-project/catapult,sahiljain/catapult,catapult-project/catapult-csm,catapult-project/catapult,benschmaus/catapult,catapult-project/catapult-csm