[Telemetry] Fix flake when proc does not contain Peak and High Water Marks.

BUG=292700
TBR=qyearsley@chromium.org

Review URL: https://codereview.chromium.org/93053002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237807 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237807