Improve support for multiselect list box accessibility on Windows.

content/browser/accessibility/browser_accessibility_win.h

Index: content/browser/accessibility/browser_accessibility_win.h
===================================================================
--- content/browser/accessibility/browser_accessibility_win.h	(revision 111700)
+++ content/browser/accessibility/browser_accessibility_win.h	(working copy)
@@ -194,6 +194,10 @@
       IAccessibleRelation** relations,
       LONG* n_relations);
 
+  CONTENT_EXPORT STDMETHODIMP get_groupPosition(LONG* group_level,
+                                                LONG* similar_items_in_group,
+                                                LONG* position_in_group);
+
   // IAccessible2 methods not implemented.
   CONTENT_EXPORT STDMETHODIMP get_extendedRole(BSTR* extended_role) {
     return E_NOTIMPL;
@@ -207,11 +211,6 @@
       LONG y) {
     return E_NOTIMPL;
   }
-  CONTENT_EXPORT STDMETHODIMP get_groupPosition(LONG* group_level,
-                                                LONG* similar_items_in_group,
-                                                LONG* position_in_group) {
-    return E_NOTIMPL;
-  }
   CONTENT_EXPORT STDMETHODIMP get_localizedExtendedRole(
       BSTR* localized_extended_role) {
     return E_NOTIMPL;
@@ -722,6 +721,9 @@
   // is initialized again but the text doesn't change.
   string16 old_text_;
 
+  // The previous state, used to see if there was a state change.
+  int32 old_ia_state_;
+
   // Relationships between this node and other nodes.
   std::vector<BrowserAccessibilityRelation*> relations_;