Updating trunk VERSION from 4389.0 to 4390.0 and incrementing major version to 90

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

Change-Id: Ic0f32e8a2f23df7f7a194a19af8f2104ea7f7bc4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2632285Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#843936}

chrome/MAJOR_BRANCH_DATE

-MAJOR_BRANCH_DATE=2020-11-13
+MAJOR_BRANCH_DATE=2021-01-15

chrome/VERSION

-MAJOR=89
+MAJOR=90
 MINOR=0
-BUILD=4389
+BUILD=4390
 PATCH=0