Reduce canonicalization when dragging

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

 /*
  * Copyright (C) 2004, 2008, 2009, 2010 Apple 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:
  * 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 186 matching lines @@
 
 void FrameCaret::paintCaret(GraphicsContext& context,
                             const LayoutPoint& paintOffset) const {
   m_displayItemClient->paintCaret(context, paintOffset, DisplayItem::kCaret);
 }
 
 bool FrameCaret::shouldBlinkCaret() const {
   if (m_caretVisibility != CaretVisibility::Visible || !isActive())
     return false;
 
-  Element* root = rootEditableElementOf(caretPosition().position());
+  Element* root =
+      rootEditableElementOf(m_selectionEditor->selectionInDOMTree().base());

[yosin_UTC9, 2017/03/16 02:30:05]

Could you move change in another CL?
This change is independent from others.

[yoichio, 2017/03/16 04:10:59]

Acknowledged.

   if (!root)
     return false;
 
   Element* focusedElement = root->document().focusedElement();
   if (!focusedElement)
     return false;
 
   return focusedElement->isShadowIncludingInclusiveAncestorOf(
       caretPosition().anchorNode());
 }
@@ skipping 11 matching lines @@
     frameView->scheduleVisualUpdateForPaintInvalidationIfNeeded();
 }
 
 void FrameCaret::recreateCaretBlinkTimerForTesting(
     RefPtr<WebTaskRunner> taskRunner) {
   m_caretBlinkTimer.reset(new TaskRunnerTimer<FrameCaret>(
       std::move(taskRunner), this, &FrameCaret::caretBlinkTimerFired));
 }
 
 }  // namespace blink