For Linux, create a ZygoteForkDelegate that uses the nacl_helper executable

chrome/app/chrome_main.cc

Index: chrome/app/chrome_main.cc
diff --git a/chrome/app/chrome_main.cc b/chrome/app/chrome_main.cc
index 3b45594d7a2c71e873f40842133e5661d4ed767b..d4f80de55b058d9232a6c2e84e76b2835b83b9b2 100644
--- a/chrome/app/chrome_main.cc
+++ b/chrome/app/chrome_main.cc
@@ -77,6 +77,7 @@
 #endif
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
+#include "chrome/common/nacl_fork_delegate_linux.h"
 #include "content/common/zygote_fork_delegate_linux.h"
 #endif
 
@@ -459,7 +460,11 @@ int RunZygote(const MainFunctionParams& main_function_params) {
     media::InitializeMediaLibrary(media_path);
 
   // This function call can return multiple times, once per fork().
-  if (!ZygoteMain(main_function_params, NULL))
+  NaClForkDelegate* nacl_delegate = new NaClForkDelegate();
+  int rval = ZygoteMain(main_function_params, nacl_delegate);
+  if (nacl_delegate)
+    delete nacl_delegate;
+  if (!rval)
     return 1;
 
   // Zygote::HandleForkRequest may have reallocated the command