Fix ordering of histograms in histograms.xml.
Fix ordering of histograms in histograms.xml.

They were ordered incorrectly as a result of two CLs landing
near the same time.

https://codereview.chromium.org/1439173003
https://codereview.chromium.org/1445863002

BUG=none
NOTRY=true

Review URL: https://codereview.chromium.org/1448943002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#359860}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk