Re-enable session_restore on mac
Re-enable session_restore on mac

BUG=511273
CQ_EXTRA_TRYBOTS=tryserver.chromium.perf:linux_perf_bisect;tryserver.chromium.perf:mac_perf_bisect

Review URL: https://codereview.chromium.org/1250453005

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#339702}

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