Added a class acting as a fake caret for accessibility.

ui/accessibility/platform/ax_platform_node_win.cc

 // Copyright 2015 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 <atlbase.h>
 #include <atlcom.h>
 #include <limits.h>
 #include <oleacc.h>
 #include <stdint.h>
 
@@ skipping 163 matching lines @@
   if (event_type == ui::AX_EVENT_SELECTION &&
       GetData().role == ui::AX_ROLE_MENU_ITEM)
     event_type = ui::AX_EVENT_FOCUS;
 
   int native_event = MSAAEvent(event_type);
   if (native_event < EVENT_MIN)
     return;
 
   ::NotifyWinEvent(native_event, hwnd, OBJID_CLIENT, -unique_id_);
 
+  if (event_type == ui::AX_EVENT_TEXT_SELECTION_CHANGED) {
+    // We also need to fire an older MSAA event used by some assistive software.

[dougt, 2017/03/28 15:23:44]

Nit: comment is odd here since we're not dispatching any events after this

+    ::NotifyWinEvent(EVENT_OBJECT_LOCATIONCHANGE, hwnd, OBJID_CARET,
+                     -unique_id_);
+  }
+
   // Keep track of objects that are a target of an alert event.
   if (event_type == ui::AX_EVENT_ALERT)
     AddAlertTarget();
 }
 
 int AXPlatformNodeWin::GetIndexInParent() {
   base::win::ScopedComPtr<IDispatch> parent_dispatch;
   base::win::ScopedComPtr<IAccessible> parent_accessible;
   if (S_OK != get_accParent(parent_dispatch.Receive()))
     return -1;
@@ skipping 998 matching lines @@
     ui::TextBoundaryDirection direction) {
   HandleSpecialTextOffset(&start_offset);
   ui::TextBoundaryType boundary = IA2TextBoundaryToTextBoundary(ia2_boundary);
   std::vector<int32_t> line_breaks;
   return static_cast<LONG>(ui::FindAccessibleTextBoundary(
       text, line_breaks, boundary, start_offset, direction,
       AX_TEXT_AFFINITY_DOWNSTREAM));
 }
 
 }  // namespace ui