Add wfh to owners for Chrome browser diagnostics.

BUG=None

Change-Id: I5bca24884e190cbe1d599360f85b250a1fe4aff0
Reviewed-on: https://chromium-review.googlesource.com/1060234Reviewed-by: Carlos Pizano <cpu@chromium.org>
Commit-Queue: Will Harris <wfh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558855}

chrome/browser/diagnostics/OWNERS

 cpu@chromium.org
+wfh@chromium.org
 
 # COMPONENT: Internals>PlatformIntegration