Fix sizing of tray details scroll views.

ash/common/system/tray/tray_details_view.cc

Index: ash/common/system/tray/tray_details_view.cc
diff --git a/ash/common/system/tray/tray_details_view.cc b/ash/common/system/tray/tray_details_view.cc
index 1b175e0ff56a475006abc50ec626c937471be593..85ca0883070bad8fa1617ff36a93a54a3653b7a7 100644
--- a/ash/common/system/tray/tray_details_view.cc
+++ b/ash/common/system/tray/tray_details_view.cc
@@ -386,7 +386,7 @@ void TrayDetailsView::Layout() {
 
   if (scroller_) {
     if (UseMd()) {
-      gfx::Size scroller_size = scroll_content_->GetPreferredSize();
+      gfx::Size scroller_size = scroller()->GetPreferredSize();
       gfx::Size pref_size = GetPreferredSize();
       scroller()->ClipHeightTo(
           0, scroller_size.height() - (pref_size.height() - height()));