Use text affinity to return correct accessible line boundaries.

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 1128 matching lines @@
 
 LONG AXPlatformNodeWin::FindBoundary(
     const base::string16& text,
     IA2TextBoundaryType ia2_boundary,
     LONG start_offset,
     ui::TextBoundaryDirection direction) {
   HandleSpecialTextOffset(text, &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));
+      text, line_breaks, boundary, start_offset, direction,
+      AX_TEXT_AFFINITY_DOWNSTREAM));
 }
 
 }  // namespace ui