Track all changed nodes during an update

chrome/common/extensions/chrome_extension_messages.h

 // 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.
 
 // Chrome-specific IPC messages for extensions.
 // Extension-related messages that aren't specific to Chrome live in
 // extensions/common/extension_messages.h.
 //
 // Multiply-included message file, hence no include guard.
 
@@ skipping 99 matching lines @@
   IPC_STRUCT_MEMBER(gfx::Vector2d, location_offset)
 
   // The tree update.
   IPC_STRUCT_MEMBER(ui::AXTreeUpdate, 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(ExtensionMsg_AccessibilityLocationChangeParams)
   // ID of the accessibility tree that this event applies to.
   IPC_STRUCT_MEMBER(int, tree_id)
 
   // ID of the object whose location is changing.
   IPC_STRUCT_MEMBER(int, id)
 
   // The object's new location info.
@@ skipping 15 matching lines @@
 // Messages sent from the renderer to the browser.
 
 
 // Sent by the renderer to implement chrome.webstore.install().
 IPC_MESSAGE_ROUTED5(ExtensionHostMsg_InlineWebstoreInstall,
                     int32_t /* install id */,
                     int32_t /* return route id */,
                     std::string /* Web Store item ID */,
                     GURL /* requestor URL */,
                     int /* listeners_mask */)