Track all changed nodes during an update

content/common/accessibility_messages.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.
 
 // IPC messages for accessibility.
 // Multiply-included message file, hence no include guard.
 
 #include "content/common/ax_content_node_data.h"
 #include "content/common/content_export.h"
 #include "content/common/view_message_enums.h"
@@ skipping 63 matching lines @@
 
 IPC_STRUCT_BEGIN(AccessibilityHostMsg_EventParams)
   // The tree update.
   IPC_STRUCT_MEMBER(content::AXContentTreeUpdate, update)
 
   // Type of event.
   IPC_STRUCT_MEMBER(ui::AXEvent, event_type)
 
   // ID of the node that the event applies to.
   IPC_STRUCT_MEMBER(int, id)
+
+  // The source of this event.
+  IPC_STRUCT_MEMBER(ui::AXEventFrom, event_from)
 IPC_STRUCT_END()
 
 IPC_STRUCT_BEGIN(AccessibilityHostMsg_LocationChangeParams)
   // ID of the object whose location is changing.
   IPC_STRUCT_MEMBER(int, id)
 
   // The object's new location info.
   IPC_STRUCT_MEMBER(ui::AXRelativeBounds, new_location)
 IPC_STRUCT_END()
 
@@ skipping 137 matching lines @@
 IPC_MESSAGE_ROUTED2(AccessibilityHostMsg_ChildFrameHitTestResult,
                     gfx::Point /* location tested */,
                     int /* node id of result */)
 
 // Sent in response to AccessibilityMsg_SnapshotTree. The callback id that was
 // passed to the request will be returned in |callback_id|, along with
 // a standalone snapshot of the accessibility tree.
 IPC_MESSAGE_ROUTED2(AccessibilityHostMsg_SnapshotResponse,
                     int /* callback_id */,
                     content::AXContentTreeUpdate)