Keep track of accessibility focus across windows.

ui/accessibility/ax_tree_data.cc

Index: ui/accessibility/ax_tree_data.cc
diff --git a/ui/accessibility/ax_tree_data.cc b/ui/accessibility/ax_tree_data.cc
index 9475a597ff5df7471e3ff10b2fb55efba700198b..5094c3b9890dfed05ed62ef64c5c35f7c4ba9b98 100644
--- a/ui/accessibility/ax_tree_data.cc
+++ b/ui/accessibility/ax_tree_data.cc
@@ -21,6 +21,7 @@ AXTreeData::AXTreeData()
       parent_tree_id(-1),
       loaded(false),
       loading_progress(0.0),
+      focus_id(-1),
       sel_anchor_object_id(-1),
       sel_anchor_offset(-1),
       sel_focus_object_id(-1),
@@ -54,6 +55,9 @@ std::string AXTreeData::ToString() const {
   if (loading_progress != 0.0)
     result += " loading_progress=" + DoubleToString(loading_progress);
 
+  if (focus_id != -1)
+    result += " focus_id=" + IntToString(focus_id);
+
   if (sel_anchor_object_id != -1) {
     result += " sel_anchor_object_id=" + IntToString(sel_anchor_object_id);
     result += " sel_anchor_offset=" + IntToString(sel_anchor_offset);
@@ -75,6 +79,7 @@ bool operator==(const AXTreeData& lhs, const AXTreeData& rhs) {
           lhs.doctype == rhs.doctype &&
           lhs.loaded == rhs.loaded &&
           lhs.loading_progress == rhs.loading_progress &&
+          lhs.focus_id == rhs.focus_id &&
           lhs.sel_anchor_object_id == rhs.sel_anchor_object_id &&
           lhs.sel_anchor_offset == rhs.sel_anchor_offset &&
           lhs.sel_focus_object_id == rhs.sel_focus_object_id &&