Modify the Chrome Linux zygote to support a nacl_helper executable,

content/common/content_switches.cc

Index: content/common/content_switches.cc
diff --git a/content/common/content_switches.cc b/content/common/content_switches.cc
index 7033c7f6b21ee491ca3df732b10ff34cb4be95c8..3e226107f78dca5a1ebb5cbdad848d1d490ea17b 100644
--- a/content/common/content_switches.cc
+++ b/content/common/content_switches.cc
@@ -274,6 +274,10 @@ const char kLogPluginMessages[]             = "log-plugin-messages";
 // (used for launching NaCl loader processes on 64-bit Windows).
 const char kNaClBrokerProcess[]             = "nacl-broker";
 
+// Enables experimental lightweight Native Client launcher for Linux
+// Value is the path to the helper binary.
+const char kNaClLinuxHelper[]               = "nacl-linux-helper";
+
 // Causes the process to run as a NativeClient loader.
 const char kNaClLoaderProcess[]             = "nacl-loader";