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

components/nacl/common/pnacl_types.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_NACL_COMMON_PNACL_TYPES_H_
 #define COMPONENTS_NACL_COMMON_PNACL_TYPES_H_
 
 // This file exists (instead of putting this type into nacl_types.h) because
 // nacl_types is built into nacl_helper in addition to chrome, and we don't
 // want to pull src/url/ into there, since it would be unnecessary bloat.
 
 #include "base/time/time.h"
 #include "url/gurl.h"
 
 namespace nacl {
 // Cache-related information about pexe files, sent from the plugin/renderer
 // to the browser.
 //
 // If you change this, you will also need to update the IPC serialization in
 // nacl_host_messages.h.
 struct PnaclCacheInfo {
   PnaclCacheInfo();
   ~PnaclCacheInfo();
   GURL pexe_url;
   int abi_version;
   int opt_level;
   base::Time last_modified;
   std::string etag;
   bool has_no_store_header;
+  bool use_subzero;
   std::string sandbox_isa;
   std::string extra_flags;
 };
 
 }  // namespace nacl
 
 #endif  // COMPONENTS_NACL_COMMON_PNACL_TYPES_H_