Add support for retrieving image thumbnails as part of 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 <stddef.h>
 
 #include <set>
 
@@ skipping 112 matching lines @@
     : tree_source_(tree_source) {
   tree_source_->Freeze();
 }
 
 ScopedFreezeBlinkAXTreeSource::~ScopedFreezeBlinkAXTreeSource() {
   tree_source_->Thaw();
 }
 
 BlinkAXTreeSource::BlinkAXTreeSource(RenderFrameImpl* render_frame)
     : render_frame_(render_frame),
-      accessibility_focus_id_(-1),
       frozen_(false) {}
 
 BlinkAXTreeSource::~BlinkAXTreeSource() {
 }
 
 void BlinkAXTreeSource::Freeze() {
   CHECK(!frozen_);
   frozen_ = true;
 
   if (render_frame_ && render_frame_->GetWebFrame())
@@ skipping 573 matching lines @@
     dst->AddIntAttribute(ui::AX_ATTR_SCROLL_Y, scrollOffset.y());
 
     const gfx::Point& minScrollOffset = src.minimumScrollOffset();
     dst->AddIntAttribute(ui::AX_ATTR_SCROLL_X_MIN, minScrollOffset.x());
     dst->AddIntAttribute(ui::AX_ATTR_SCROLL_Y_MIN, minScrollOffset.y());
 
     const gfx::Point& maxScrollOffset = src.maximumScrollOffset();
     dst->AddIntAttribute(ui::AX_ATTR_SCROLL_X_MAX, maxScrollOffset.x());
     dst->AddIntAttribute(ui::AX_ATTR_SCROLL_Y_MAX, maxScrollOffset.y());
   }
+
+  if (dst->id == image_data_node_id_) {
+    dst->AddStringAttribute(ui::AX_ATTR_IMAGE_DATA_URL,
+                            src.imageDataUrl(max_image_data_size_).utf8());
+  }
 }
 
 blink::WebDocument BlinkAXTreeSource::GetMainDocument() const {
   CHECK(frozen_);
   return document_;
 }
 
 WebAXObject BlinkAXTreeSource::ComputeRoot() const {
   if (!explicit_root_.isNull())
     return explicit_root_;
 
   if (!render_frame_ || !render_frame_->GetWebFrame())
     return WebAXObject();
 
   WebDocument document = render_frame_->GetWebFrame()->document();
   if (!document.isNull())
     return document.accessibilityObject();
 
   return WebAXObject();
 }
 
 }  // namespace content