Updating trunk VERSION from 3438.0 to 3439.0

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

Change-Id: I90298cf52d077cb75dd0167f318307940af7e3a8
Reviewed-on: https://chromium-review.googlesource.com/1069180Reviewed-by: chrome-release-bot@chromium.org <chrome-release-bot@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560913}

chrome/VERSION

 MAJOR=68
 MINOR=0
-BUILD=3438
+BUILD=3439
 PATCH=0