Updating trunk VERSION from 3390.0 to 3391.0

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

Change-Id: I10ab13cc1eba5f515d163fe10ea24e3bcbc88416
Reviewed-on: https://chromium-review.googlesource.com/999314Reviewed-by: chrome-release-bot@chromium.org <chrome-release-bot@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548652}

chrome/VERSION

 MAJOR=67
 MINOR=0
-BUILD=3390
+BUILD=3391
 PATCH=0