Modify the Chrome Linux zygote to support a nacl_helper executable,

content/common/content_switches.h

Index: content/common/content_switches.h
diff --git a/content/common/content_switches.h b/content/common/content_switches.h
index f48e69a8b8b18ffd998a1de0f17932bd15806bf2..1b2384fc2e14bf4ca2c019fe494e97f7a69f9c22 100644
--- a/content/common/content_switches.h
+++ b/content/common/content_switches.h
@@ -92,6 +92,10 @@ extern const char kLogPluginMessages[];
 // TODO(jam): this doesn't belong in content.
 extern const char kNaClBrokerProcess[];
 extern const char kNaClLoaderProcess[];
+// TODO(bradchen): remove kNaClLinuxHelper switch.
+// This switch enables the experimental lightweight nacl_helper for Linux.
+// It will be going away soon, when the helper is enabled permanently.
+extern const char kNaClLinuxHelper[];
 extern const char kNoDisplayingInsecureContent[];
 extern const char kNoJsRandomness[];
 extern const char kNoReferrers[];