[ash-md] Stacks child layers properly for sticky header rows

ash/common/system/tray/tray_popup_utils.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/common/system/tray/tray_popup_utils.h"
 
 #include "ash/common/ash_constants.h"
 #include "ash/common/ash_view_ids.h"
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/session/session_state_delegate.h"
@@ skipping 272 matching lines @@
   toggle->SetAccessibleName(l10n_util::GetStringUTF16(accessible_name_id));
   return toggle;
 }
 
 void TrayPopupUtils::ConfigureAsStickyHeader(views::View* view) {
   view->set_id(VIEW_ID_STICKY_HEADER);
   view->set_background(
       views::Background::CreateSolidBackground(kBackgroundColor));
   view->SetBorder(
       views::CreateEmptyBorder(gfx::Insets(kMenuSeparatorVerticalPadding, 0)));
+  view->SetPaintToLayer(true);
+  view->layer()->SetFillsBoundsOpaquely(false);
+}
+
+void TrayPopupUtils::ShowStickyHeaderSeparator(views::View* view,
+                                               bool show_separator) {
+  if (show_separator) {
+    view->SetBorder(views::CreatePaddedBorder(
+        views::CreateSolidSidedBorder(0, 0, kSeparatorWidth, 0,
+                                      kHorizontalSeparatorColor),
+        gfx::Insets(kMenuSeparatorVerticalPadding, 0,
+                    kMenuSeparatorVerticalPadding - kSeparatorWidth, 0)));
+  } else {
+    view->SetBorder(views::CreateEmptyBorder(
+        gfx::Insets(kMenuSeparatorVerticalPadding, 0)));
+  }
+  view->SchedulePaint();
 }
 
 void TrayPopupUtils::ConfigureContainer(TriView::Container container,
                                         views::View* container_view) {
   container_view->SetLayoutManager(
       CreateDefaultLayoutManager(container).release());
 }
 
 views::LabelButton* TrayPopupUtils::CreateTrayPopupBorderlessButton(
     views::ButtonListener* listener,
@@ skipping 153 matching lines @@
 bool TrayPopupUtils::CanOpenWebUISettings(LoginStatus status) {
   // TODO(tdanderson): Consider moving this into WmShell, or introduce a
   // CanShowSettings() method in each delegate type that has a
   // ShowSettings() method.
   return status != LoginStatus::NOT_LOGGED_IN &&
          status != LoginStatus::LOCKED &&
          !WmShell::Get()->GetSessionStateDelegate()->IsInSecondaryLoginScreen();
 }
 
 }  // namespace ash