Fixes possible crash in menus on views/gtk. The crash would happen if...

views/controls/menu/native_menu_gtk.h

Index: views/controls/menu/native_menu_gtk.h
===================================================================
--- views/controls/menu/native_menu_gtk.h	(revision 35711)
+++ views/controls/menu/native_menu_gtk.h	(working copy)
@@ -63,6 +63,12 @@
   // state is changed by |UpdateStates()| API.
   bool suppress_activate_signal_;
 
+  // Did the user select something from the menu?
+  bool menu_activated_;
+
+  // If menu_activated_ is true, this is the index of the item.
+  int activated_index_;
+
   DISALLOW_COPY_AND_ASSIGN(NativeMenuGtk);
 };