Update nacl enum comment to point to correct histograms.xml file.
Update nacl enum comment to point to correct histograms.xml file.

BUG=none
NOTRY=true

Review URL: https://codereview.chromium.org/433973002

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@13578 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client