Have each SandboxedProcessLauncherDelegate maintain a zygote.

content/public/common/sandboxed_process_launcher_delegate.h

Index: content/public/common/sandboxed_process_launcher_delegate.h
diff --git a/content/public/common/sandboxed_process_launcher_delegate.h b/content/public/common/sandboxed_process_launcher_delegate.h
index 39e2cc88d263dd3fc7e3ce2930190cc3de4bcd4c..b7ec5555a0e0ab3547178a48b816d6197b9fef11 100644
--- a/content/public/common/sandboxed_process_launcher_delegate.h
+++ b/content/public/common/sandboxed_process_launcher_delegate.h
@@ -21,6 +21,13 @@ class TargetPolicy;
 
 namespace content {
 
+#if defined(OS_LINUX)
+class ZygoteCommunication;
+using ZygoteHandle = ZygoteCommunication*;
+#else
+struct ZygoteHandle {};
+#endif
+
 // Allows a caller of StartSandboxedProcess or
 // BrowserChildProcessHost/ChildProcessLauncher to control the sandbox policy,
 // i.e. to loosen it if needed.
@@ -51,7 +58,7 @@ class CONTENT_EXPORT SandboxedProcessLauncherDelegate {
 
 #elif defined(OS_POSIX)
   // Override this to return true to use the setuid sandbox.
-  virtual bool ShouldUseZygote();
+  virtual ZygoteHandle* GetZygote();
 
   // Override this if the process needs a non-empty environment map.
   virtual base::EnvironmentMap GetEnvironment();