Make VisibleSelection::AppendTrailingWhitespace() as const function

third_party/WebKit/Source/core/editing/SelectionController.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  * Copyright (C) 2015 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ skipping 511 matching lines @@
     if (new_selection.RootEditableElement() &&
         pos.DeepEquivalent() == VisiblePositionInFlatTree::LastPositionInNode(
                                     *new_selection.RootEditableElement())
                                     .DeepEquivalent())
       return false;
 
     visibility = HandleVisibility::kVisible;
   }
 
   if (append_trailing_whitespace == AppendTrailingWhitespace::kShouldAppend)
-    new_selection.AppendTrailingWhitespace();
+    new_selection = new_selection.AppendTrailingWhitespace();
 
   return UpdateSelectionForMouseDownDispatchingSelectStart(
       inner_node,
       ExpandSelectionToRespectUserSelectAll(inner_node, new_selection),
       kWordGranularity, visibility);
 }
 
 void SelectionController::SelectClosestMisspellingFromHitTestResult(
     const HitTestResult& result,
     AppendTrailingWhitespace append_trailing_whitespace) {
@@ skipping 23 matching lines @@
     return;
   }
 
   Node* container_node = marker_position.ComputeContainerNode();
   const PositionInFlatTree start(container_node, marker->StartOffset());
   const PositionInFlatTree end(container_node, marker->EndOffset());
   VisibleSelectionInFlatTree new_selection = CreateVisibleSelection(
       SelectionInFlatTree::Builder().Collapse(start).Extend(end).Build());
 
   if (append_trailing_whitespace == AppendTrailingWhitespace::kShouldAppend)
-    new_selection.AppendTrailingWhitespace();
+    new_selection = new_selection.AppendTrailingWhitespace();
 
   UpdateSelectionForMouseDownDispatchingSelectStart(
       inner_node,
       ExpandSelectionToRespectUserSelectAll(inner_node, new_selection),
       kWordGranularity, HandleVisibility::kNotVisible);
 }
 
 bool SelectionController::SelectClosestWordFromMouseEvent(
     const MouseEventWithHitTestResults& result) {
   if (!mouse_down_may_start_select_)
@@ skipping 626 matching lines @@
 
 bool IsExtendingSelection(const MouseEventWithHitTestResults& event) {
   bool is_mouse_down_on_link_or_image =
       event.IsOverLink() || event.GetHitTestResult().GetImage();
   return (event.Event().GetModifiers() & WebInputEvent::Modifiers::kShiftKey) !=
              0 &&
          !is_mouse_down_on_link_or_image;
 }
 
 }  // namespace blink