Change AdditionalOptions to a list from a string. This fixes compilation errors when building bench within chrome.
Change AdditionalOptions to a list from a string. This fixes compilation errors
when building bench within chrome.

BUG=363
TEST=Build bench through a chrome checkout on windows
Review URL: http://codereview.appspot.com/5045042

git-svn-id: e8541e15acce502a64c929015570ad1648e548cd@2275 2bbb7eff-a529-9590-31e7-b0007b416f81

mrobinson/skia,metajack/skia,metajack/skia,Cue/skia,mrobinson/skia,Cue/skia,mrobinson/skia,metajack/skia,Cue/skia,mrobinson/skia,metajack/skia,Cue/skia,mrobinson/skia