Implement Element.scrollIntoView for scroll-behavior: smooth.

third_party/WebKit/Source/core/page/Page.h

Index: third_party/WebKit/Source/core/page/Page.h
diff --git a/third_party/WebKit/Source/core/page/Page.h b/third_party/WebKit/Source/core/page/Page.h
index efb2332c1a7de40e4ebc8d45738d4e77f8972829..aad427e09f122813eada8f28242b06b62b12fcfb 100644
--- a/third_party/WebKit/Source/core/page/Page.h
+++ b/third_party/WebKit/Source/core/page/Page.h
@@ -66,6 +66,7 @@ class PluginData;
 class PointerLockController;
 class ScopedPageSuspender;
 class ScrollingCoordinator;
+class SmoothScrollSequencer;
 class Settings;
 class ConsoleMessageStorage;
 class SpellCheckerClient;
@@ -177,6 +178,8 @@ class CORE_EXPORT Page final : public GarbageCollectedFinalized<Page>,
 
   ScrollingCoordinator* scrollingCoordinator();
 
+  SmoothScrollSequencer* smoothScrollSequencer();
+
   ClientRectList* nonFastScrollableRects(const LocalFrame*);
 
   Settings& settings() const { return *m_settings; }
@@ -302,6 +305,7 @@ class CORE_EXPORT Page final : public GarbageCollectedFinalized<Page>,
   const std::unique_ptr<PageScaleConstraintsSet> m_pageScaleConstraintsSet;
   const Member<PointerLockController> m_pointerLockController;
   Member<ScrollingCoordinator> m_scrollingCoordinator;
+  Member<SmoothScrollSequencer> m_smoothScrollSequencer;
   const Member<BrowserControls> m_browserControls;
   const Member<ConsoleMessageStorage> m_consoleMessageStorage;
   const Member<EventHandlerRegistry> m_eventHandlerRegistry;