Have each SandboxedProcessLauncherDelegate maintain a zygote.

content/public/browser/zygote_host_linux.h

Index: content/public/browser/zygote_host_linux.h
diff --git a/content/public/browser/zygote_host_linux.h b/content/public/browser/zygote_host_linux.h
index ebe5ee7387fb67dc3e7be5349eb009d9e3a1787b..d48a268e709c1ec5c0d6207dbf3c4839b1f1313a 100644
--- a/content/public/browser/zygote_host_linux.h
+++ b/content/public/browser/zygote_host_linux.h
@@ -24,11 +24,11 @@ class ZygoteHost {
   virtual ~ZygoteHost() {}
 
   // Returns the pid of the Zygote process.
-  virtual pid_t GetPid() const = 0;
+  virtual bool IsZygotePid(pid_t pid) = 0;
 
   // Returns an int which is a bitmask of kSandboxLinux* values. Only valid
   // after the first render has been forked.
-  virtual int GetSandboxStatus() const = 0;
+  virtual int GetRendererSandboxStatus() const = 0;
 
   // Adjust the OOM score of the given renderer's PID.  The allowed
   // range for the score is [0, 1000], where higher values are more