Get rid of redundant layout tree update related to selection

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 1605 matching lines @@
 }
 
 void Editor::setMarkedTextMatchesAreHighlighted(bool flag) {
   if (flag == m_areMarkedTextMatchesHighlighted)
     return;
 
   m_areMarkedTextMatchesHighlighted = flag;
   frame().document()->markers().repaintMarkers(DocumentMarker::TextMatch);
 }
 
+SelectionType computeSelectionType(const SelectionInDOMTree& selection) {
+  if (selection.isNone())

[yoichio, 2017/02/17 04:35:16]

As commented, we should rename to computeIsNone() or so.

[yosin_UTC9, 2017/02/17 05:14:49]

This will be done in another patch.
To make this patch as small as possible.

+    return NoSelection;
+  if (selection.isCaret() && selection.granularity() == CharacterGranularity)
+    return CaretSelection;
+  return RangeSelection;
+}
+
 void Editor::respondToChangedSelection(
     const Position& oldSelectionStart,
     FrameSelection::SetSelectionOptions options) {
   spellChecker().respondToChangedSelection(oldSelectionStart, options);
-  client().respondToChangedSelection(&frame(),
-                                     frame().selection().getSelectionType());
+  client().respondToChangedSelection(
+      &frame(), computeSelectionType(frame().selection().selectionInDOMTree()));
   setStartNewKillRingSequence(true);
 }
 
 SpellChecker& Editor::spellChecker() const {
   return frame().spellChecker();
 }
 
 void Editor::toggleOverwriteModeEnabled() {
   m_overwriteModeEnabled = !m_overwriteModeEnabled;
   frame().selection().setShouldShowBlockCursor(m_overwriteModeEnabled);
@@ skipping 60 matching lines @@
 
 DEFINE_TRACE(Editor) {
   visitor->trace(m_frame);
   visitor->trace(m_lastEditCommand);
   visitor->trace(m_undoStack);
   visitor->trace(m_mark);
   visitor->trace(m_typingStyle);
 }
 
 }  // namespace blink