Fix typos in BUILD.gn source lists
Fix typos in BUILD.gn source lists

"foo,cc" is not the same as "foo.cc"

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/326193002

Patch from James Robinson <jamesr@chromium.org>.

git-svn-id: f98b9d40cb02301bc76fa9e1b46ee668158567fd@21765 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh