Implement Element.scrollIntoView for scroll-behavior: smooth.

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

Index: third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
index 769acc39df44b05836e2d8ab1259afcd765a904f..09a44edf3f6e81b0f9ebe032ce4082a293c82170 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
@@ -37,6 +37,7 @@
 #include "platform/scroll/MainThreadScrollingReason.h"
 #include "platform/scroll/ProgrammaticScrollAnimator.h"
 #include "platform/scroll/ScrollbarTheme.h"
+#include "platform/scroll/SmoothScrollSequencer.h"
 
 static const int kPixelsPerLineStep = 40;
 static const float kMinFractionToStepWhenPaging = 0.875f;
@@ -227,7 +228,7 @@ void ScrollableArea::ProgrammaticScrollHelper(const ScrollOffset& offset,
   CancelScrollAnimation();
 
   if (scroll_behavior == kScrollBehaviorSmooth)
-    GetProgrammaticScrollAnimator().AnimateToOffset(offset);
+    GetProgrammaticScrollAnimator().AnimateToOffset(offset, true);
   else
     GetProgrammaticScrollAnimator().ScrollToOffsetWithoutAnimation(offset);
 }
@@ -255,6 +256,7 @@ void ScrollableArea::UserScrollHelper(const ScrollOffset& offset,
 LayoutRect ScrollableArea::ScrollIntoView(const LayoutRect& rect_in_content,
                                           const ScrollAlignment& align_x,
                                           const ScrollAlignment& align_y,
+                                          bool is_smooth,
                                           ScrollType) {
   // TODO(bokan): This should really be implemented here but ScrollAlignment is
   // in Core which is a dependency violation.