Implement Element.scrollIntoView for scroll-behavior: smooth.

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

Index: third_party/WebKit/Source/core/page/Page.cpp
diff --git a/third_party/WebKit/Source/core/page/Page.cpp b/third_party/WebKit/Source/core/page/Page.cpp
index 6dc4b2180bc29db3eaaf4c604531a8cad016befb..ece401687520e4a6acf014132bf94b7cc8fe913c 100644
--- a/third_party/WebKit/Source/core/page/Page.cpp
+++ b/third_party/WebKit/Source/core/page/Page.cpp
@@ -61,6 +61,7 @@
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/loader/fetch/ResourceFetcher.h"
 #include "platform/plugins/PluginData.h"
+#include "platform/scroll/SmoothScrollSequencer.h"
 #include "public/platform/Platform.h"
 
 namespace blink {
@@ -171,6 +172,13 @@ PageScaleConstraintsSet& Page::GetPageScaleConstraintsSet() {
   return *page_scale_constraints_set_;
 }
 
+SmoothScrollSequencer* Page::GetSmoothScrollSequencer() {
+  if (!smooth_scroll_sequencer_)
+    smooth_scroll_sequencer_ = SmoothScrollSequencer::Create();
+
+  return smooth_scroll_sequencer_.Get();
+}
+
 const PageScaleConstraintsSet& Page::GetPageScaleConstraintsSet() const {
   return *page_scale_constraints_set_;
 }
@@ -621,6 +629,7 @@ DEFINE_TRACE(Page) {
   visitor->Trace(context_menu_controller_);
   visitor->Trace(pointer_lock_controller_);
   visitor->Trace(scrolling_coordinator_);
+  visitor->Trace(smooth_scroll_sequencer_);
   visitor->Trace(browser_controls_);
   visitor->Trace(console_message_storage_);
   visitor->Trace(event_handler_registry_);