Remove style spans to follow the styles of the block element

third_party/WebKit/Source/core/editing/commands/ReplaceSelectionCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009, 2010, 2011 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:
  * 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 776 matching lines @@
             || isHTMLStyleElement(*node)
             || isHTMLTitleElement(*node)) {
             next = NodeTraversal::nextSkippingChildren(*node);
             fragment.removeNode(node);
         } else {
             next = NodeTraversal::next(*node);
         }
     }
 }
 
+static bool followBlockElementStyle(const Node* node)
+{
+    if (!node->isHTMLElement())
+        return false;
+
+    const HTMLElement& element = toHTMLElement(*node);
+    return element.hasTagName(liTag)

[yosin_UTC9, 2016/06/28 01:27:50]

Is it better to check "display:block", "display:table-cell",
"display:list-item", etc, rather than tag name?
Since, Web author can override meaning of tag name, e.g. "<div
style="display:inline">...</div>"

[joone, 2016/06/28 08:41:43]

Done.

+        || element.hasTagName(preTag)
+        || element.hasTagName(tdTag)
+        || element.hasTagName(h1Tag)
+        || element.hasTagName(h2Tag)
+        || element.hasTagName(h3Tag)
+        || element.hasTagName(h4Tag)
+        || element.hasTagName(h5Tag);

[yosin_UTC9, 2016/06/28 01:27:50]

Could you explain why do you omit H6?
https://developer.mozilla.org/de/docs/Web/HTML/Element/h1-h6

[joone, 2016/06/28 08:41:43]

I just missed h6.

+}
+
 // Remove style spans before insertion if they are unnecessary.  It's faster because we'll
 // avoid doing a layout.
 static bool handleStyleSpansBeforeInsertion(ReplacementFragment& fragment, const Position& insertionPos)
 {
     Node* topNode = fragment.firstChild();
     if (!isHTMLSpanElement(topNode))
         return false;
 
     // Handling the case where we are doing Paste as Quotation or pasting into quoted content is more complicated (see handleStyleSpans)
     // and doesn't receive the optimization.
     if (isMailPasteAsQuotationHTMLBlockQuoteElement(topNode) || enclosingNodeOfType(firstPositionInOrBeforeNode(topNode), isMailHTMLBlockquoteElement, CanCrossEditingBoundary))
         return false;
 
-    // Remove style spans to follow the styles of list item when |fragment| becomes a list item.
-    // See bug http://crbug.com/335955.
+    // Remove style spans to follow the styles of parent block element when |fragment| becomes a part of it.
+    // See bugs http://crbug.com/226941 and http://crbug.com/335955.
     HTMLSpanElement* wrappingStyleSpan = toHTMLSpanElement(topNode);
-    if (isListItem(enclosingBlock(insertionPos.anchorNode()))) {
+    const Node* node = insertionPos.anchorNode();
+    // |node| can be an inline element like <br> under <li>
+    // e.g.) editing/execCommand/switch-list-type.html
+    //       editing/deleting/backspace-merge-into-block.html
+    if (node->layoutObject() && node->layoutObject()->isInline()) {

[yosin_UTC9, 2016/06/28 01:27:50]

Let's use Node::computedStyle() rather than layout object to reduce dependency
of layout tree.

[joone, 2016/06/28 08:41:43]

Done.

+        if (!(node = enclosingBlock(insertionPos.anchorNode())))
+            return false;
+    }
+
+    if (followBlockElementStyle(node)) {
         fragment.removeNodePreservingChildren(wrappingStyleSpan);
         return true;
     }
 
     // Either there are no style spans in the fragment or a WebKit client has added content to the fragment
     // before inserting it.  Look for and handle style spans after insertion.
     if (!isLegacyAppleHTMLSpanElement(topNode))
         return false;
 
     EditingStyle* styleAtInsertionPos = EditingStyle::create(insertionPos.parentAnchoredEquivalent());
@@ skipping 905 matching lines @@
     visitor->trace(m_startOfInsertedContent);
     visitor->trace(m_endOfInsertedContent);
     visitor->trace(m_insertionStyle);
     visitor->trace(m_documentFragment);
     visitor->trace(m_startOfInsertedRange);
     visitor->trace(m_endOfInsertedRange);
     CompositeEditCommand::trace(visitor);
 }
 
 } // namespace blink