Disable synchronous XMLHttpRequests in platform app documents.

webkit/glue/webpreferences.h

Index: webkit/glue/webpreferences.h
diff --git a/webkit/glue/webpreferences.h b/webkit/glue/webpreferences.h
index 48c98811b0d8f018d026e77ab361e96cba5f1a9e..c016fea653ec9e7d802d3a9039c453b06a45bd02 100644
--- a/webkit/glue/webpreferences.h
+++ b/webkit/glue/webpreferences.h
@@ -5,7 +5,7 @@
 // A struct for managing webkit's settings.
 //
 // Adding new values to this class probably involves updating
-// WebKit::WebSettings, common/render_messages.cc, browser/tab_contents/
+// WebKit::WebSettings, content/common/view_messages.h, browser/tab_contents/
 // render_view_host_delegate_helper.cc, and browser/profiles/profile.cc.
 
 #ifndef WEBKIT_GLUE_WEBPREFERENCES_H__
@@ -128,6 +128,7 @@ struct WEBKIT_GLUE_EXPORT WebPreferences {
   int max_untiled_layer_width;
   int max_untiled_layer_height;
   bool fixed_position_creates_stacking_context;
+  bool sync_xhr_in_documents_enabled;
 
   // We try to keep the default values the same as the default values in
   // chrome, except for the cases where it would require lots of extra work for