Switched to using |AXPosition| for calculating word and line boundaries on Windows.

content/browser/accessibility/ax_platform_position.cc

 // Copyright 2016 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/ax_platform_position.h"
 
 #include "content/browser/accessibility/browser_accessibility.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
 #include "ui/accessibility/ax_enums.h"
 
@@ skipping 91 matching lines @@
 // On some platforms, most objects are represented in the text of their parents
 // with a special (embedded object) character and not with their actual text
 // contents.
 int AXPlatformPosition::MaxTextOffsetInParent() const {
 #if defined(OS_WIN) || \
     (defined(OS_LINUX) && defined(USE_X11) && !defined(OS_CHROMEOS))
   if (IsNullPosition())
     return INVALID_OFFSET;
   if (GetAnchor()->IsTextOnlyObject())
     return MaxTextOffset();
+  // Not all objects in the internal accessibility tree are exposed to platform
+  // APIs.
+  if (GetAnchor()->PlatformIsChildOfLeaf())
+    return MaxTextOffset();
   return 1;
 #else
   return MaxTextOffset();
 #endif
 }
 
 bool AXPlatformPosition::IsInLineBreak() const {
   if (IsNullPosition())
     return false;
 
@@ skipping 34 matching lines @@
   int previous_on_line_id;
   if (!node ||
       !node->GetIntAttribute(ui::AX_ATTR_PREVIOUS_ON_LINE_ID,
                              &previous_on_line_id)) {
     return INVALID_ANCHOR_ID;
   }
   return static_cast<int32_t>(previous_on_line_id);
 }
 
 }  // namespace content