GitLab

Added process_mac.cc with implementations of IsProcessBackgrounded() and
SetProcessBackgrounded().

BUG=460102

Originally Committed: https://crrev.com/e3bb10f7860a1d553c85293bd7d7615c0e7f0fd9
Reverted: https://crrev.com/ce6226a7ffe2c1cb7ac5f6cf34b56b8d217686b9

Review URL: https://codereview.chromium.org/989703002

Cr-Commit-Position: refs/heads/master@{#330464}