Manually update trunk VERSION from 3408.0 to 3409.0

This brings things back in sync after a failed branching.

TBR=govind@google.com
NOTRY=true

Bug: 825063
Change-Id: Id141a41135fab3b5b4736746d5b790659a254bf5
Reviewed-on: https://chromium-review.googlesource.com/1028665
Commit-Queue: Michael Moss <mmoss@chromium.org>
Reviewed-by: Michael Moss <mmoss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553697}

chrome/VERSION

 MAJOR=68
 MINOR=0
-BUILD=3408
+BUILD=3409
 PATCH=0