Add a switch for using PNaCl Subzero and use it for -O0 translation.

components/nacl/browser/pnacl_host_unittest.cc

Index: components/nacl/browser/pnacl_host_unittest.cc
diff --git a/components/nacl/browser/pnacl_host_unittest.cc b/components/nacl/browser/pnacl_host_unittest.cc
index 3f2d3efadfb2e56c7fef72d534bbf7aed9c0bb84..960f8d5fb166220dff59fe6478b088a1cfb7c2d5 100644
--- a/components/nacl/browser/pnacl_host_unittest.cc
+++ b/components/nacl/browser/pnacl_host_unittest.cc
@@ -115,6 +115,7 @@ static nacl::PnaclCacheInfo GetTestCacheInfo() {
   info.abi_version = 0;
   info.opt_level = 0;
   info.has_no_store_header = false;
+  info.use_subzero = false;
   return info;
 }