gm: Include system_preferences.h in mac file.
gm: Include system_preferences.h in mac file.

This fixes the FIXME in there.

R=epoger@google.com

Review URL: https://codereview.appspot.com/6576049

git-svn-id: e8541e15acce502a64c929015570ad1648e548cd@5692 2bbb7eff-a529-9590-31e7-b0007b416f81

MatChung/color-emoji.skia,hbwhlklive/color-emoji.skia,Frankie-666/color-emoji.skia,hbwhlklive/color-emoji.skia,MatChung/color-emoji.skia,MatChung/color-emoji.skia,Frankie-666/color-emoji.skia,Hankuo/color-emoji.skia,MatChung/color-emoji.skia,Frankie-666/color-emoji.skia,Hankuo/color-emoji.skia,Hankuo/color-emoji.skia,MatChung/color-emoji.skia,Frankie-666/color-emoji.skia,Hankuo/color-emoji.skia,Frankie-666/color-emoji.skia,Hankuo/color-emoji.skia,hbwhlklive/color-emoji.skia,hbwhlklive/color-emoji.skia,Hankuo/color-emoji.skia,MatChung/color-emoji.skia,Frankie-666/color-emoji.skia,hbwhlklive/color-emoji.skia,hbwhlklive/color-emoji.skia