Keep track of accessibility focus across windows.

chrome/browser/ui/aura/accessibility/ax_tree_source_aura.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/aura/accessibility/ax_tree_source_aura.h"
 
 #include <stddef.h>
 
 #include <vector>
 
@@ skipping 45 matching lines @@
   AXAuraObjWrapper* obj = AXAuraObjCache::GetInstance()->Get(id);
   if (obj)
     obj->ShowContextMenu();
 }
 
 ui::AXTreeData AXTreeSourceAura::GetTreeData() const {
   ui::AXTreeData tree_data;
   tree_data.tree_id = 0;
   tree_data.loaded = true;
   tree_data.loading_progress = 1.0;
+  AXAuraObjWrapper* focus = AXAuraObjCache::GetInstance()->GetFocus();
+  if (focus)
+    tree_data.focus_id = focus->GetID();
   return tree_data;
 }
 
 AXAuraObjWrapper* AXTreeSourceAura::GetRoot() const {
   return root_.get();
 }
 
 AXAuraObjWrapper* AXTreeSourceAura::GetFromId(int32_t id) const {
   if (id == root_->GetID())
     return root_.get();
@@ skipping 57 matching lines @@
 
   std::vector<AXAuraObjWrapper*> children;
   root->GetChildren(&children);
 
   prefix += prefix[0];
   for (size_t i = 0; i < children.size(); ++i)
     output += ToString(children[i], prefix);
 
   return output;
 }