Use a single, generic, global zygote to temporarily resolve perf regressions.

components/nacl/browser/nacl_process_host.cc

Index: components/nacl/browser/nacl_process_host.cc
diff --git a/components/nacl/browser/nacl_process_host.cc b/components/nacl/browser/nacl_process_host.cc
index 3b57e145015f46abe09ffc6803fde16b7b271721..6e97a66de87fb7c5177f8feae24b931222621b69 100644
--- a/components/nacl/browser/nacl_process_host.cc
+++ b/components/nacl/browser/nacl_process_host.cc
@@ -186,7 +186,10 @@ class NaClSandboxedProcessLauncherDelegate
   }
 #elif defined(OS_POSIX)
 #if !defined(OS_MACOSX)
-  content::ZygoteHandle* GetZygote() override { return &g_nacl_zygote; }
+  content::ZygoteHandle* GetZygote() override {
+    static content::ZygoteHandle zygote = content::GetGenericZygote();
+    return &zygote;
+  }
 #endif  // !defined(OS_MACOSX)
 
   base::ScopedFD TakeIpcFd() override { return std::move(ipc_fd_); }