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

content/browser/zygote_host/zygote_handle_linux.cc

 // Copyright 2016 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.
 
 #include "content/public/browser/zygote_handle_linux.h"
 
 #include "content/browser/zygote_host/zygote_communication_linux.h"
 
 namespace content {
 
 ZygoteHandle CreateZygote() {
   ZygoteHandle zygote = new ZygoteCommunication();
   zygote->Init();
   return zygote;
 }
 
+ZygoteHandle GetGenericZygote() {

[mdempsky, 2016/01/28 23:25:40]

Change to:

  ZygoteHandle* GetGenericZygote() {
    static ZygoteHandle zygote;
    return &zygote;
  }

so all of the SandboxedProcessLauncherDelegate::GetZygote() overloads become
something like

  ZygoteHandle* FooDelegate::GetZygote() {
    return content::GetGenericZygote();
  }

[Greg K, 2016/01/29 00:41:03]

Done.

+  static ZygoteHandle zygote = CreateZygote();
+  return zygote;
+}
+
 }  // namespace content