Updating trunk VERSION from 4267.0 to 4268.0

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

Change-Id: I39d53fcdbd2cb647356cb4fa253f797f2647b51e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2417643Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#808206}

chrome/VERSION

 MAJOR=87
 MINOR=0
-BUILD=4267
+BUILD=4268
 PATCH=0