Add a WebContentsImpl API to snapshot the accessibility tree.

content/renderer/accessibility/blink_ax_tree_source.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 "content/renderer/accessibility/blink_ax_tree_source.h"
 
 #include <set>
 
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
@@ skipping 99 matching lines @@
 BlinkAXTreeSource::BlinkAXTreeSource(RenderFrameImpl* render_frame)
     : render_frame_(render_frame),
       node_to_frame_routing_id_map_(NULL),
       node_to_browser_plugin_instance_id_map_(NULL),
       accessibility_focus_id_(-1) {
 }
 
 BlinkAXTreeSource::~BlinkAXTreeSource() {
 }
 
+void BlinkAXTreeSource::SetRoot(blink::WebAXObject root) {
+  root_ = root;
+}
+
 bool BlinkAXTreeSource::IsInTree(blink::WebAXObject node) const {
   const blink::WebAXObject& root = GetRoot();
   while (IsValid(node)) {
     if (node.equals(root))
       return true;
     node = GetParent(node);
   }
   return false;
 }
 
 void BlinkAXTreeSource::CollectChildFrameIdMapping(
     std::map<int32, int>* node_to_frame_routing_id_map,
     std::map<int32, int>* node_to_browser_plugin_instance_id_map) {
   node_to_frame_routing_id_map_ = node_to_frame_routing_id_map;
   node_to_browser_plugin_instance_id_map_ =
       node_to_browser_plugin_instance_id_map;
 }
 
 blink::WebAXObject BlinkAXTreeSource::GetRoot() const {
+  if (!root_.isNull())
+    return root_;
   return GetMainDocument().accessibilityObject();
 }
 
 blink::WebAXObject BlinkAXTreeSource::GetFromId(int32 id) const {
   return GetMainDocument().accessibilityObjectFromID(id);
 }
 
 int32 BlinkAXTreeSource::GetId(blink::WebAXObject node) const {
   return node.axID();
 }
@@ skipping 452 matching lines @@
     AddIntListAttributeFromWebObjects(ui::AX_ATTR_OWNS_IDS, owns, dst);
 }
 
 blink::WebDocument BlinkAXTreeSource::GetMainDocument() const {
   if (render_frame_ && render_frame_->GetWebFrame())
     return render_frame_->GetWebFrame()->document();
   return WebDocument();
 }
 
 }  // namespace content