Disk cache: fix the name of some histograms.
Disk cache: fix the name of some histograms.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/2824059

git-svn-id: http://src.chromium.org/svn/trunk/src@53075 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: c2324afaaa09a6ae99265642bf14852e3b3e7cae
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser