Let insertNewLineInQuotedContent not do anything out of a quote element

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

 /*
  * Copyright (C) 2005 Apple Computer, 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 56 matching lines @@
   VisiblePosition next = nextPositionOf(visiblePosition);
   return next.isNull() ||
          !next.deepEquivalent().anchorNode()->isDescendantOf(node);
 }
 
 }  // namespace
 
 BreakBlockquoteCommand::BreakBlockquoteCommand(Document& document)
     : CompositeEditCommand(document) {}
 
+static HTMLQuoteElement* topBlockquoteOf(const Position& start) {
+  // This is a position equivalent to the caret.  We use |downstream()| so that
+  // |position| will be in the first node that we need to move (there are a few
+  // exceptions to this, see |doApply|).
+  const Position& position = mostForwardCaretPosition(start);
+

[yosin_UTC9, 2017/03/21 05:30:44]

nit: We don't need to have an extra blank line here.

+  return toHTMLQuoteElement(
+      highestEnclosingNodeOfType(position, isMailHTMLBlockquoteElement));
+}
+
 void BreakBlockquoteCommand::doApply(EditingState* editingState) {
   if (endingSelection().isNone())
     return;
 
+  if (!topBlockquoteOf(endingSelection().start()))
+    return;
+
   // Delete the current selection.
   if (endingSelection().isRange()) {
     deleteSelection(editingState, false, false);
     if (editingState->isAborted())
       return;
   }
 
   // This is a scenario that should never happen, but we want to
   // make sure we don't dereference a null pointer below.
 
   DCHECK(!endingSelection().isNone());
 
   if (endingSelection().isNone())
     return;
 
   document().updateStyleAndLayoutIgnorePendingStylesheets();
 
   VisiblePosition visiblePos = endingSelection().visibleStart();
 
   // pos is a position equivalent to the caret.  We use downstream() so that pos
   // will be in the first node that we need to move (there are a few exceptions
   // to this, see below).
   Position pos = mostForwardCaretPosition(endingSelection().start());
 
   // Find the top-most blockquote from the start.
-  HTMLQuoteElement* topBlockquote = toHTMLQuoteElement(
-      highestEnclosingNodeOfType(pos, isMailHTMLBlockquoteElement));
+  HTMLQuoteElement* const topBlockquote =
+      topBlockquoteOf(endingSelection().start());
   if (!topBlockquote || !topBlockquote->parentNode())
     return;
 
   HTMLBRElement* breakElement = HTMLBRElement::create(document());
 
   bool isLastVisPosInNode =
       isLastVisiblePositionInNode(visiblePos, topBlockquote);
 
   // If the position is at the beginning of the top quoted content, we don't
   // need to break the quote. Instead, insert the break before the blockquote,
@@ skipping 150 matching lines @@
 
   // Put the selection right before the break.
   setEndingSelection(SelectionInDOMTree::Builder()
                          .collapse(Position::beforeNode(breakElement))
                          .setIsDirectional(endingSelection().isDirectional())
                          .build());
   rebalanceWhitespace();
 }
 
 }  // namespace blink