Include "build/build_config.h" explicitly because we test the OS_WIN macro.
Include "build/build_config.h" explicitly because we test the
OS_WIN macro.

R=willchan
BUG=43142
TEST=No compilation error.
Review URL: http://codereview.chromium.org/1929005

git-svn-id: http://src.chromium.org/svn/trunk/src@46367 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 9df0e2ea7ef365d6caeba391cbc2486e0696c70d
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