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

components/nacl/renderer/ppb_nacl_private_impl.cc

Index: components/nacl/renderer/ppb_nacl_private_impl.cc
diff --git a/components/nacl/renderer/ppb_nacl_private_impl.cc b/components/nacl/renderer/ppb_nacl_private_impl.cc
index fb5e6dc9e356f52fef1a591e386cada970e43eaf..42203581c9f43d6b877787dcad27f536cf718c52 100644
--- a/components/nacl/renderer/ppb_nacl_private_impl.cc
+++ b/components/nacl/renderer/ppb_nacl_private_impl.cc
@@ -267,6 +267,7 @@ class ManifestServiceProxy : public ManifestServiceChannel::Delegate {
     PP_PNaClOptions pnacl_options;
     pnacl_options.translate = PP_FALSE;
     pnacl_options.is_debug = PP_FALSE;
+    pnacl_options.use_subzero = PP_FALSE;
     pnacl_options.opt_level = 2;
     bool is_helper_process = process_type_ == kPNaClTranslatorProcessType;
     if (!ManifestResolveKey(pp_instance_, is_helper_process, key, &url,
@@ -1058,6 +1059,15 @@ PP_Bool ManifestGetProgramURL(PP_Instance instance,
                               &error_info)) {
     *pp_full_url = ppapi::StringVar::StringToPPVar(full_url);
     *pp_uses_nonsfi_mode = PP_FromBool(uses_nonsfi_mode);
+    // Check if we should use Subzero (x86-32 / non-debugging case for now).
+    if (pnacl_options->opt_level == 0 && !pnacl_options->is_debug &&
+        strcmp(GetSandboxArch(), "x86-32") == 0 &&
+        base::CommandLine::ForCurrentProcess()->HasSwitch(
+            switches::kEnablePNaClSubzero)) {
+      pnacl_options->use_subzero = PP_TRUE;
+      // Subzero -O2 is closer to LLC -O0, so indicate -O2.
+      pnacl_options->opt_level = 2;
+    }
     return PP_TRUE;
   }
 
@@ -1099,7 +1109,8 @@ bool ManifestResolveKey(PP_Instance instance,
 
 PP_Bool GetPNaClResourceInfo(PP_Instance instance,
                              PP_Var* llc_tool_name,
-                             PP_Var* ld_tool_name) {
+                             PP_Var* ld_tool_name,
+                             PP_Var* subzero_tool_name) {
   static const char kFilename[] = "chrome://pnacl-translator/pnacl.json";
   NexeLoadManager* load_manager = GetNexeLoadManager(instance);
   DCHECK(load_manager);
@@ -1176,18 +1187,30 @@ PP_Bool GetPNaClResourceInfo(PP_Instance instance,
   if (json_data.isMember("pnacl-llc-name")) {
     Json::Value json_name = json_data["pnacl-llc-name"];
     if (json_name.isString()) {
-      std::string llc_tool_name_str = json_name.asString();
-      *llc_tool_name = ppapi::StringVar::StringToPPVar(llc_tool_name_str);
+      *llc_tool_name = ppapi::StringVar::StringToPPVar(json_name.asString());
     }
   }
 
   if (json_data.isMember("pnacl-ld-name")) {
     Json::Value json_name = json_data["pnacl-ld-name"];
     if (json_name.isString()) {
-      std::string ld_tool_name_str = json_name.asString();
-      *ld_tool_name = ppapi::StringVar::StringToPPVar(ld_tool_name_str);
+      *ld_tool_name = ppapi::StringVar::StringToPPVar(json_name.asString());
     }
   }
+
+  if (json_data.isMember("pnacl-sz-name")) {
+    Json::Value json_name = json_data["pnacl-sz-name"];
+    if (json_name.isString()) {
+      *subzero_tool_name =
+          ppapi::StringVar::StringToPPVar(json_name.asString());
+    }
+  } else {
+    // TODO(jvoung): remove fallback after one chrome release
+    // or when we bump the kMinPnaclVersion.
+    // TODO(jvoung): Just use strings instead of PP_Var!
+    *subzero_tool_name = ppapi::StringVar::StringToPPVar("pnacl-sz.nexe");
+  }
+
   return PP_TRUE;
 }