Add support for retrieving image thumbnails as part of the accessibility tree.

content/renderer/accessibility/render_accessibility_impl.h

 // Copyright (c) 2012 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.
 
 #ifndef CONTENT_RENDERER_ACCESSIBILITY_RENDER_ACCESSIBILITY_IMPL_H_
 #define CONTENT_RENDERER_ACCESSIBILITY_RENDER_ACCESSIBILITY_IMPL_H_
 
 #include <vector>
 
 #include "base/containers/hash_tables.h"
@@ skipping 108 matching lines @@
   void OnDestruct() override;
 
   // Handlers for messages from the browser to the renderer.
   void OnPerformAction(const ui::AXActionData& data);
   void OnEventsAck(int ack_token);
   void OnFatalError();
   void OnReset(int reset_token);
 
   void OnHitTest(const gfx::Point& point);
   void OnSetAccessibilityFocus(const blink::WebAXObject& obj);
+  void OnGetImageData(const blink::WebAXObject& obj, const gfx::Size& max_size);
   void AddPluginTreeToUpdate(AXContentTreeUpdate* update);
   void ScrollPlugin(int id_to_make_visible);
 
   // Events from Blink are collected until they are ready to be
   // sent to the browser.
   std::vector<AccessibilityHostMsg_EventParams> pending_events_;
 
   // The adapter that exposes Blink's accessibility tree to AXTreeSerializer.
   BlinkAXTreeSource tree_source_;
 
@@ skipping 33 matching lines @@
 
   // So we can queue up tasks to be executed later.
   base::WeakPtrFactory<RenderAccessibilityImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderAccessibilityImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_ACCESSIBILITY_RENDERER_ACCESSIBILITY_H_