Show small notification icons in notification tray

ash/common/system/tray/tray_background_view.cc

Index: ash/common/system/tray/tray_background_view.cc
diff --git a/ash/common/system/tray/tray_background_view.cc b/ash/common/system/tray/tray_background_view.cc
index 3e26c5069993d2872ef9ae0d0f4602002b223bb3..4b11c766d22e8a1e6f5f19827c1872f9d5cb6a36 100644
--- a/ash/common/system/tray/tray_background_view.cc
+++ b/ash/common/system/tray/tray_background_view.cc
@@ -175,6 +175,11 @@ void TrayBackgroundView::TrayContainer::SetAlignment(ShelfAlignment alignment) {
   UpdateLayout();
 }
 
+void TrayBackgroundView::TrayContainer::SetMargin(const gfx::Insets& margin) {
+  margin_ = margin;
+  UpdateLayout();
+}
+
 gfx::Size TrayBackgroundView::TrayContainer::GetPreferredSize() const {
   if (size_.IsEmpty())
     return views::View::GetPreferredSize();
@@ -208,7 +213,9 @@ void TrayBackgroundView::TrayContainer::UpdateLayout() {
     // dark background.
     const int padding = 3;
     SetBorder(
-        views::Border::CreateEmptyBorder(padding, padding, padding, padding));
+        views::Border::CreateEmptyBorder(gfx::Insets(padding) + margin_));
+  } else {
+    SetBorder(views::Border::CreateEmptyBorder(margin_));
   }
 
   views::BoxLayout* layout = new views::BoxLayout(orientation, 0, 0, 0);