Updating trunk VERSION from 3863.0 to 3864.0

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

Change-Id: I2d7f8bfa090f643a494d2d9965634e638fc29bde
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1716325Reviewed-by: chrome-release-bot@chromium.org <chrome-release-bot@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680312}

chrome/VERSION

 MAJOR=77
 MINOR=0
-BUILD=3863
+BUILD=3864
 PATCH=0