Adding in optional coverage trybots for nacl.
Adding in optional coverage trybots for nacl.

BUG=http://code.google.com/p/nativeclient/issues/detail?id=2732
TEST=None
R=cmp@chromium.org

Review URL: http://codereview.chromium.org/10169021

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@133280 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build