Do not send redundant selectionchange-events (decouple focus)

third_party/WebKit/Source/core/page/FocusController.cpp

 /*
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nuanti Ltd.
  *
  * 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 1048 matching lines @@
   ScopedFocusNavigation scope =
       ScopedFocusNavigation::ownedByShadowHost(shadowHost);
   return findFocusableElementAcrossFocusScopes(WebFocusTypeForward, scope);
 }
 
 static bool relinquishesEditingFocus(const Element& element) {
   DCHECK(hasEditableStyle(element));
   return element.document().frame() && rootEditableElement(element);
 }
 
-static void clearSelectionIfNeeded(LocalFrame* oldFocusedFrame,
-                                   LocalFrame* newFocusedFrame,
-                                   Element* newFocusedElement) {
-  if (!oldFocusedFrame || !newFocusedFrame)
-    return;
-
-  if (oldFocusedFrame->document() != newFocusedFrame->document())
-    return;
-
-  FrameSelection& selection = oldFocusedFrame->selection();
-  if (selection.isNone())
-    return;
-
-  Node* selectionStartNode = selection.selection().start().anchorNode();
-  if (selectionStartNode == newFocusedElement ||
-      selectionStartNode->isDescendantOf(newFocusedElement))
-    return;
-
-  if (!enclosingTextControl(selectionStartNode))
-    return;
-
-  if (selectionStartNode->isInShadowTree() &&
-      selectionStartNode->ownerShadowHost() == newFocusedElement)
-    return;
-
-  selection.clear();
-}
-
 bool FocusController::setFocusedElement(Element* element,
                                         Frame* newFocusedFrame) {
   return setFocusedElement(
       element, newFocusedFrame,
       FocusParams(SelectionBehaviorOnFocus::None, WebFocusTypeNone, nullptr));
 }
 
 bool FocusController::setFocusedElement(Element* element,
                                         Frame* newFocusedFrame,
                                         const FocusParams& params) {
@@ skipping 16 matching lines @@
   Document* newDocument = nullptr;
   if (element)
     newDocument = &element->document();
   else if (newFocusedFrame && newFocusedFrame->isLocalFrame())
     newDocument = toLocalFrame(newFocusedFrame)->document();
 
   if (newDocument && oldDocument == newDocument &&
       newDocument->focusedElement() == element)
     return true;
 
-  if (newFocusedFrame && newFocusedFrame->isLocalFrame())
-    clearSelectionIfNeeded(oldFocusedFrame, toLocalFrame(newFocusedFrame),
-                           element);
-
   if (oldDocument && oldDocument != newDocument)
     oldDocument->clearFocusedElement();
 
   if (newFocusedFrame && !newFocusedFrame->page()) {
     setFocusedFrame(nullptr);
     return false;
   }
   setFocusedFrame(newFocusedFrame);
 
   if (newDocument) {
@@ skipping 267 matching lines @@
     it->focusedFrameChanged();
 }
 
 DEFINE_TRACE(FocusController) {
   visitor->trace(m_page);
   visitor->trace(m_focusedFrame);
   visitor->trace(m_focusChangedObservers);
 }
 
 }  // namespace blink