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

chrome/browser/ui/aura/accessibility/automation_manager_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/automation_manager_aura.h"
 
 #include <stddef.h>
 
 #include <vector>
 
@@ skipping 99 matching lines @@
       current_tree_->ShowContextMenu(data.target_node_id);
       break;
     case ui::AX_ACTION_SET_ACCESSIBILITY_FOCUS:
       // Sent by ChromeVox but doesn't need to be handled by aura.
       break;
     case ui::AX_ACTION_SET_SEQUENTIAL_FOCUS_NAVIGATION_STARTING_POINT:
       // Sent by ChromeVox but doesn't need to be handled by aura.
       break;
     case ui::AX_ACTION_BLUR:
     case ui::AX_ACTION_DECREMENT:
+    case ui::AX_ACTION_GET_IMAGE_DATA:
     case ui::AX_ACTION_HIT_TEST:
     case ui::AX_ACTION_INCREMENT:
     case ui::AX_ACTION_REPLACE_SELECTED_TEXT:
     case ui::AX_ACTION_SCROLL_TO_POINT:
     case ui::AX_ACTION_SET_SCROLL_OFFSET:
     case ui::AX_ACTION_SET_VALUE:
       // Not implemented yet.
       NOTREACHED();
       break;
     case ui::AX_ACTION_NONE:
@@ skipping 63 matching lines @@
 
   processing_events_ = false;
   auto pending_events_copy = pending_events_;
   pending_events_.clear();
   for (size_t i = 0; i < pending_events_copy.size(); ++i) {
     SendEvent(context,
               pending_events_copy[i].first,
               pending_events_copy[i].second);
   }
 }