Updating trunk VERSION from 4270.0 to 4271.0

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

Change-Id: I898f32c538d81d34cd79744ec313f1eff1c39a4f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2420969Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#808771}

chrome/VERSION

 MAJOR=87
 MINOR=0
-BUILD=4270
+BUILD=4271
 PATCH=0