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

content/browser/accessibility/browser_accessibility_manager.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_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_
 #define CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 168 matching lines @@
   // For testing only, register a function to be called when focus changes
   // in any BrowserAccessibilityManager.
   static void SetFocusChangeCallbackForTesting(const base::Closure& callback);
 
   // Accessibility actions. All of these are implemented asynchronously
   // by sending a message to the renderer to perform the respective action
   // on the given node.  See the definition of |ui::AXActionData| for more
   // information about each of these actions.
   void Decrement(const BrowserAccessibility& node);
   void DoDefaultAction(const BrowserAccessibility& node);
+  void GetImageData(const BrowserAccessibility& node,
+                    const gfx::Size& max_size);
   void HitTest(const gfx::Point& point);
   void Increment(const BrowserAccessibility& node);
   void ScrollToMakeVisible(
       const BrowserAccessibility& node, gfx::Rect subfocus);
   void ScrollToPoint(
       const BrowserAccessibility& node, gfx::Point point);
   void SetFocus(const BrowserAccessibility& node);
   void SetScrollOffset(const BrowserAccessibility& node, gfx::Point offset);
   void SetValue(
       const BrowserAccessibility& node, const base::string16& value);
@@ skipping 260 matching lines @@
   // node within that parent tree. It's computed as needed and cached for
   // speed so that it can be accessed quickly if it hasn't changed.
   int parent_node_id_from_parent_tree_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserAccessibilityManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_