Added a class acting as a fake caret for accessibility.

content/browser/accessibility/browser_accessibility_manager_win.cc

 // 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.
 
 #include "content/browser/accessibility/browser_accessibility_manager_win.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <vector>
@@ skipping 186 matching lines @@
   if (win_event_type == EVENT_OBJECT_REORDER &&
       target->PlatformChildCount() == 0) {
     return BrowserAccessibilityEvent::NotNeededOnThisPlatform;
   }
 
   // Pass the negation of this node's unique id in the |child_id|
   // argument to NotifyWinEvent; the AT client will then call get_accChild
   // on the HWND's accessibility object and pass it that same id, which
   // we can use to retrieve the IAccessible for this node.
   LONG child_id = -target->unique_id();
+  if (event_type == ui::AX_EVENT_DOCUMENT_SELECTION_CHANGED) {
+    // We also need to fire an older MSAA event used by some assistive software.
+    ::NotifyWinEvent(EVENT_OBJECT_LOCATIONCHANGE, hwnd, OBJID_CARET, child_id);

[dmazzoni, 2017/04/17 05:07:34]

I don't think we want this here, because this means Windows Magnifier
won't work because it doesn't enable accessibility. I suggest calling this in
RenderWidgetHostViewBase::OnSelectionBoundsChanged instead.

+  }
+
   ::NotifyWinEvent(win_event_type, hwnd, OBJID_CLIENT, child_id);
-
   return BrowserAccessibilityEvent::Sent;
 }
 
 bool BrowserAccessibilityManagerWin::CanFireEvents() {
   BrowserAccessibilityDelegate* root_delegate = GetDelegateFromRootManager();
   if (!root_delegate)
     return false;
   HWND hwnd = root_delegate->AccessibilityGetAcceleratedWidget();
   return hwnd != nullptr;
 }
@@ skipping 80 matching lines @@
     DCHECK(changed_node);
     BrowserAccessibility* obj = GetFromAXNode(changed_node);
     if (obj && obj->IsNative() && !obj->PlatformIsChildOfLeaf()) {
       ToBrowserAccessibilityWin(obj)->UpdateStep3FireEvents(
           changes[i].type == AXTreeDelegate::SUBTREE_CREATED);
     }
   }
 }
 
 }  // namespace content