Only works on Vista or later, since it uses condition variables. Review URL: https://codereview.appspot.com/6812062 git-svn-id: http://skia.googlecode.com/svn/trunk@6225 2bbb7eff-a529-9590-31e7-b0007b416f81
Skia-ized from https://codereview.appspot.com/6755043/ TODO: Use SkThread and platform independent features. Review URL: https://codereview.appspot.com/6777064 git-svn-id: http://skia.googlecode.com/svn/trunk@6217 2bbb7eff-a529-9590-31e7-b0007b416f81