Change npapi.h header guard to match npapi-headers version
Change npapi.h header guard to match npapi-headers version

BUG=42645
TEST=Everything still compiles

Review URL: http://codereview.chromium.org/2002008

git-svn-id: http://src.chromium.org/svn/trunk/src@46927 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 724c828925325bc8f6e06e94afd31d2d63075f0d
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