Updating trunk VERSION from 3420.0 to 3421.0

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

Change-Id: I55617b91fb756ad4f2d94b02dbc6b39b812cf7ce
Reviewed-on: https://chromium-review.googlesource.com/1044890Reviewed-by: chrome-release-bot@chromium.org <chrome-release-bot@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556155}

chrome/VERSION

 MAJOR=68
 MINOR=0
-BUILD=3420
+BUILD=3421
 PATCH=0