Updating trunk VERSION from 4155.0 to 4156.0

# This is an automated release commit.
# Do not revert without consulting chrome-pmo@google.com.
NOAUTOREVERT=true
TBR=govind@chromium.org

Change-Id: I1c87ca2f4b9de688f18e382c187c13911950a3cd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2214622Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#771462}

chrome/VERSION

 MAJOR=85
 MINOR=0
-BUILD=4155
+BUILD=4156
 PATCH=0