Rename {Author,UserAgent}ShadowRoot to {Open,Closed}ShadowRoot.

Source/core/layout/LayoutTheme.cpp

Index: Source/core/layout/LayoutTheme.cpp
diff --git a/Source/core/layout/LayoutTheme.cpp b/Source/core/layout/LayoutTheme.cpp
index 5933606f8afb638a032610cebf7dd0911fc710e9..c3e303aad40448063d349a59d0faf27d01518d37 100644
--- a/Source/core/layout/LayoutTheme.cpp
+++ b/Source/core/layout/LayoutTheme.cpp
@@ -823,7 +823,7 @@ void LayoutTheme::paintSliderTicks(LayoutObject* o, const PaintInfo& paintInfo,
     bool isHorizontal = part ==  SliderHorizontalPart;
 
     IntSize thumbSize;
-    LayoutObject* thumbRenderer = input->userAgentShadowRoot()->getElementById(ShadowElementNames::sliderThumb())->renderer();
+    LayoutObject* thumbRenderer = input->closedShadowRoot()->getElementById(ShadowElementNames::sliderThumb())->renderer();
     if (thumbRenderer) {
         const LayoutStyle& thumbStyle = thumbRenderer->styleRef();
         int thumbWidth = thumbStyle.width().intValue();
@@ -838,7 +838,7 @@ void LayoutTheme::paintSliderTicks(LayoutObject* o, const PaintInfo& paintInfo,
     int tickRegionSideMargin = 0;
     int tickRegionWidth = 0;
     IntRect trackBounds;
-    LayoutObject* trackRenderer = input->userAgentShadowRoot()->getElementById(ShadowElementNames::sliderTrack())->renderer();
+    LayoutObject* trackRenderer = input->closedShadowRoot()->getElementById(ShadowElementNames::sliderTrack())->renderer();
     // We can ignoring transforms because transform is handled by the graphics context.
     if (trackRenderer)
         trackBounds = trackRenderer->absoluteBoundingBoxRectIgnoringTransforms();