Use text affinity to return correct accessible line boundaries.

ui/accessibility/platform/ax_platform_node_win.cc

Index: ui/accessibility/platform/ax_platform_node_win.cc
diff --git a/ui/accessibility/platform/ax_platform_node_win.cc b/ui/accessibility/platform/ax_platform_node_win.cc
index ac83e27d280b32ca15feb777c6ae99a73070c5bf..814f383c19f99844267f47977d6ea6ac319f9f3e 100644
--- a/ui/accessibility/platform/ax_platform_node_win.cc
+++ b/ui/accessibility/platform/ax_platform_node_win.cc
@@ -1146,7 +1146,8 @@ LONG AXPlatformNodeWin::FindBoundary(
   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