Decrease range and add more buckets to Prerender PLT histograms.
Decrease range and add more buckets to Prerender PLT histograms.

The current granularity [500ms between buckets at peak points] makes it difficult to compare performance.

BUG=None
TEST=None

Review URL: http://codereview.chromium.org/6802010

git-svn-id: http://src.chromium.org/svn/trunk/src@80649 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 51e90b82db798a03b52ac4fdd153ea6c8a498d4a
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