mtklein@chromium -> @google

Change-Id: Id41fd940ee0316b9677bb55f68cac6eb499356b6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2023189
Auto-Submit: Mike Klein <mtklein@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Cr-Commit-Position: refs/heads/master@{#735883}

third_party/zlib/OWNERS

 agl@chromium.org
 cavalcantii@chromium.org
 cblume@chromium.org
-mtklein@chromium.org
+mtklein@google.com
 scroggo@google.com
 
 # COMPONENT: Internals