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

content/browser/utility_process_host_impl.cc

Index: content/browser/utility_process_host_impl.cc
diff --git a/content/browser/utility_process_host_impl.cc b/content/browser/utility_process_host_impl.cc
index 447685a3382e8310ab61e8c4044c1dc5c34b0d9f..b4a6b0c4dda4758752fd9b416e9de43b3fd47b36 100644
--- a/content/browser/utility_process_host_impl.cc
+++ b/content/browser/utility_process_host_impl.cc
@@ -104,7 +104,8 @@ class UtilitySandboxedProcessLauncherDelegate
   ZygoteHandle* GetZygote() override {
     if (no_sandbox_ || !exposed_dir_.empty())
       return nullptr;
-    return &g_utility_zygote;
+    static ZygoteHandle zygote = GetGenericZygote();
+    return &zygote;
   }
 #endif  // !defined(OS_MACOSX) && !defined(OS_ANDROID)
   base::EnvironmentMap GetEnvironment() override { return env_; }