Updating trunk VERSION from 4208.0 to 4209.0

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

Change-Id: I6f871712c18e353845e2c971e056d5a1fa42b65e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2309451Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#790222}

chrome/VERSION

 MAJOR=86
 MINOR=0
-BUILD=4208
+BUILD=4209
 PATCH=0