Updating trunk VERSION from 4277.0 to 4278.0

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

Change-Id: I79e12433c7174345f6a921eb234efcf8e5ce4eeb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2437694Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#811529}

chrome/VERSION

 MAJOR=87
 MINOR=0
-BUILD=4277
+BUILD=4278
 PATCH=0