Downsample thumbnail by powers of two before doing lanczos
Downsample thumbnail by powers of two before doing lanczos

This speeds up the resizing portion of thumbnailing from 40ms->15ms on my linux z600 at nearly fullscreen resolution.  Thumbnail resizing times on weaker hardware (like netbooks) has been observed in the 150ms+ range, so hopefully this is a proportional speedup there as well.

TEST=none
BUG=62820

Review URL: http://codereview.chromium.org/4846002

git-svn-id: http://src.chromium.org/svn/trunk/src@65982 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: a509e2438d92f2f68028670e5df3f634a83e7621
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