Fix beta builds

The extension's beta name strings were missing.

Change-Id: I0245671c627aced507a9c6460bd6b852aaf1ebaa
diff --git a/release.bash b/release.bash
index d361848..16eaa19 100644
--- a/release.bash
+++ b/release.bash
@@ -87,7 +87,7 @@
 
 if [[ $channel == "beta" ]]; then
   # Change manifest.json to label the release as beta
-  set_manifest_field "name" "__MSG_appBetaName__"
+  set_manifest_field "name" "__MSG_name_beta__"
 fi
 
 # Create ZIP file for upload to the Chrome Web Store