Rewrite renderer accessibility to not use WebAccessibilityCache.

content/common/view_messages.h

 // Copyright (c) 2011 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 page rendering.
 // Multiply-included message file, hence no include guard.
 
 #include "base/process.h"
 #include "base/shared_memory.h"
 #include "content/common/common_param_traits.h"
@@ skipping 443 matching lines @@
   IPC_STRUCT_MEMBER(bool, was_fetched_via_proxy)
 
   // Serialized history item state to store in the navigation entry.
   IPC_STRUCT_MEMBER(std::string, content_state)
 IPC_STRUCT_END()
 
 IPC_STRUCT_BEGIN(ViewHostMsg_AccessibilityNotification_Params)
   // Type of notification.
   IPC_STRUCT_MEMBER(ViewHostMsg_AccEvent::Value, notification_type)
 
+  // ID of the node that the notification applies to.
+  IPC_STRUCT_MEMBER(int, id)
+
   // The accessibility node tree.
-  IPC_STRUCT_MEMBER(webkit_glue::WebAccessibility, acc_obj)
+  IPC_STRUCT_MEMBER(webkit_glue::WebAccessibility, acc_tree)
+
+  // Whether children are included in this tree, otherwise it's just an
+  // update to this one node and existing children are left in place.
+  IPC_STRUCT_MEMBER(bool, includes_children)
 IPC_STRUCT_END()
 
 
 IPC_STRUCT_BEGIN(ViewHostMsg_RunFileChooser_Params)
   IPC_STRUCT_MEMBER(ViewHostMsg_RunFileChooser_Mode::Value, mode)
 
   // Title to be used for the dialog. This may be empty for the default title,
   // which will be either "Open" or "Save" depending on the mode.
   IPC_STRUCT_MEMBER(string16, title)
 
@@ skipping 1470 matching lines @@
 
 // Requests to lock the mouse. Will result in a ViewMsg_LockMouse_ACK message
 // being sent back.
 IPC_MESSAGE_ROUTED0(ViewHostMsg_LockMouse)
 
 // Requests to unlock the mouse. A ViewMsg_MouseLockLost message will be sent
 // whenever the mouse is unlocked (which may or may not be caused by
 // ViewHostMsg_UnlockMouse).
 IPC_MESSAGE_ROUTED0(ViewHostMsg_UnlockMouse)