Updating trunk VERSION from 4103.0 to 4104.0 and incrementing major version to 84

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

Change-Id: I2b93a21cd325c3c74804302c2652503835c0eed4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2134921Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#756144}

chrome/MAJOR_BRANCH_DATE

-MAJOR_BRANCH_DATE=2020-03-13
+MAJOR_BRANCH_DATE=2020-04-03

chrome/VERSION

-MAJOR=83
+MAJOR=84
 MINOR=0
-BUILD=4103
+BUILD=4104
 PATCH=0