Implement Element.scrollIntoView for scroll-behavior: smooth.

third_party/WebKit/Source/core/frame/FrameView.h

Index: third_party/WebKit/Source/core/frame/FrameView.h
diff --git a/third_party/WebKit/Source/core/frame/FrameView.h b/third_party/WebKit/Source/core/frame/FrameView.h
index 32f6a9dfea394b49053edd465a881117538dcb5b..d41910db243db0253901774ae3c2af34745965cf 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.h
+++ b/third_party/WebKit/Source/core/frame/FrameView.h
@@ -51,6 +51,7 @@
 #include "platform/graphics/GraphicsLayerClient.h"
 #include "platform/scroll/ScrollTypes.h"
 #include "platform/scroll/Scrollbar.h"
+#include "platform/scroll/SmoothScrollSequencer.h"
 #include "platform/wtf/Allocator.h"
 #include "platform/wtf/AutoReset.h"
 #include "platform/wtf/Forward.h"
@@ -474,12 +475,15 @@ class CORE_EXPORT FrameView final
   LayoutRect ScrollIntoView(const LayoutRect& rect_in_content,
                             const ScrollAlignment& align_x,
                             const ScrollAlignment& align_y,
+                            bool is_smooth,
                             ScrollType = kProgrammaticScroll) override;
 
   // The window that hosts the FrameView. The FrameView will communicate scrolls
   // and repaints to the host window in the window's coordinate space.
   PlatformChromeClient* GetChromeClient() const;
 
+  SmoothScrollSequencer* GetSmoothScrollSequencer() const override;
+
   // Functions for child manipulation and inspection.
   bool IsSelfVisible() const {
     return self_visible_;