Add sizing changes for Refactored MessageCenter

We do not need any bottom inset for the separate message center bubble.
Also, need to clip scroller height based on clear all button visibility.

Bug: 958020
Change-Id: Ie4f0966f2de97f841cf975fcc7810c82761b2de2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1730091
Commit-Queue: Ahmed Mehfooz <amehfooz@chromium.org>
Reviewed-by: Tim Song <tengs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683669}

ash/system/message_center/unified_message_center_view.cc

@@ -51,9 +51,13 @@ class ScrollerContentsView : public views::View {
  public:
   ScrollerContentsView(UnifiedMessageListView* message_list_view,
                        views::ButtonListener* listener) {
+    int bottom_padding = features::IsUnifiedMessageCenterRefactorEnabled()
+                             ? 0
+                             : kUnifiedNotificationCenterSpacing;
+
     auto* contents_layout = SetLayoutManager(std::make_unique<views::BoxLayout>(
         views::BoxLayout::Orientation::kVertical,
-        gfx::Insets(0, 0, kUnifiedNotificationCenterSpacing, 0)));
+        gfx::Insets(0, 0, bottom_padding, 0)));
     contents_layout->set_cross_axis_alignment(
         views::BoxLayout::CrossAxisAlignment::kStretch);
     AddChildView(message_list_view);
@@ -293,7 +297,10 @@ UnifiedMessageCenterView::~UnifiedMessageCenterView() {
 }
 
 void UnifiedMessageCenterView::SetMaxHeight(int max_height) {
-  scroller_->ClipHeightTo(0, max_height);
+  int max_scroller_height = max_height;
+  if (stacking_counter_->GetVisible())
+    max_scroller_height -= kStackingNotificationCounterHeight;
+  scroller_->ClipHeightTo(0, max_scroller_height);
 }
 
 void UnifiedMessageCenterView::SetAvailableHeight(int available_height) {
@@ -313,6 +320,10 @@ void UnifiedMessageCenterView::OnNotificationSlidOut() {
 void UnifiedMessageCenterView::ListPreferredSizeChanged() {
   UpdateVisibility();
   PreferredSizeChanged();
+
+  if (features::IsUnifiedMessageCenterRefactorEnabled())
+    SetMaxHeight(available_height_);
+
   Layout();
 
   if (GetWidget() && !GetWidget()->IsClosed())