Reland 72421 - Enable TCP Keep-Alive packets for Windows.
Reland 72421 - Enable TCP Keep-Alive packets for Windows.

Dropped the DCHECk since it seems some Windows version don't initialize the unused variable.

BUG=27400
TEST=none

Review URL: http://codereview.chromium.org/6242011

git-svn-id: http://src.chromium.org/svn/trunk/src@72429 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: fd8c35ae9b271659e6080746fb6ee48e048213c3
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