Tweak some things to be compatible with libpng 1.4.
Tweak some things to be compatible with libpng 1.4.

libpng 1.2 should still work too.

BUG=32805
TEST=compiles on tryservers and locally against libpng 1.4

Review URL: http://codereview.chromium.org/569009

git-svn-id: http://src.chromium.org/svn/trunk/src@38188 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 1854e25e728172ea764a0cda1f8137df77410474
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