Disable the special behaviour of document.cookie in platform apps.

chrome/browser/extensions/extension_webkit_preferences.cc

Index: chrome/browser/extensions/extension_webkit_preferences.cc
diff --git a/chrome/browser/extensions/extension_webkit_preferences.cc b/chrome/browser/extensions/extension_webkit_preferences.cc
index b15f33988cead6e5897f6211faf39546b2ccecfa..1b7c6829410376543e1921a65b7b06294eb0dcc7 100644
--- a/chrome/browser/extensions/extension_webkit_preferences.cc
+++ b/chrome/browser/extensions/extension_webkit_preferences.cc
@@ -39,6 +39,7 @@ void SetPreferences(const extensions::Extension* extension,
     webkit_prefs->databases_enabled = false;
     webkit_prefs->local_storage_enabled = false;
     webkit_prefs->sync_xhr_in_documents_enabled = false;
+    webkit_prefs->cookie_enabled = false;
   }
 
   // Enable WebGL features that regular pages can't access, since they add