Implement Element.scrollIntoView for scroll-behavior: smooth.

third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  * Copyright (C) 2008, 2011 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 231 matching lines @@
   // TODO(bokan): The userScroll method should probably be modified to call this
   //              method and ScrollAnimatorBase to have a simpler
   //              animateToOffset method like the ProgrammaticScrollAnimator.
   ASSERT(scrollBehavior == ScrollBehaviorInstant);
   scrollAnimator().scrollToOffsetWithoutAnimation(ScrollOffset(x, y));
 }
 
 LayoutRect ScrollableArea::scrollIntoView(const LayoutRect& rectInContent,
                                           const ScrollAlignment& alignX,
                                           const ScrollAlignment& alignY,
-                                          ScrollType) {
+                                          ScrollType,
+                                          ScrollBehavior) {
   // TODO(bokan): This should really be implemented here but ScrollAlignment is
   // in Core which is a dependency violation.
   ASSERT_NOT_REACHED();
   return LayoutRect();
 }
 
 void ScrollableArea::scrollOffsetChanged(const ScrollOffset& offset,
                                          ScrollType scrollType) {
   TRACE_EVENT0("blink", "ScrollableArea::scrollOffsetChanged");
 
@@ skipping 398 matching lines @@
   return IntSize(std::max(0, size.width() - verticalScrollbarWidth()),
                  std::max(0, size.height() - horizontalScrollbarHeight()));
 }
 
 DEFINE_TRACE(ScrollableArea) {
   visitor->trace(m_scrollAnimator);
   visitor->trace(m_programmaticScrollAnimator);
 }
 
 }  // namespace blink