Add a card background to the app list search result groups.

ui/app_list/views/tile_item_view.cc

Index: ui/app_list/views/tile_item_view.cc
diff --git a/ui/app_list/views/tile_item_view.cc b/ui/app_list/views/tile_item_view.cc
index a679bc1f4b93183bf13fca434d3b3ec8c6a6cc80..7be7319fa0bd3e8cdbce38762c82b6027ac950cf 100644
--- a/ui/app_list/views/tile_item_view.cc
+++ b/ui/app_list/views/tile_item_view.cc
@@ -35,8 +35,6 @@ TileItemView::TileItemView()
   ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
   title_->SetAutoColorReadabilityEnabled(false);
   title_->SetEnabledColor(kGridTitleColor);
-  title_->set_background(views::Background::CreateSolidBackground(
-      kLabelBackgroundColor));
   title_->SetFontList(rb.GetFontList(kItemTextFontStyle));
   title_->SetHorizontalAlignment(gfx::ALIGN_CENTER);
 
@@ -47,6 +45,10 @@ TileItemView::TileItemView()
 TileItemView::~TileItemView() {
 }
 
+void TileItemView::SetTitleBackgroundColor(SkColor color) {
+  title_->set_background(views::Background::CreateSolidBackground(color));
+}
+
 void TileItemView::SetIcon(const gfx::ImageSkia& icon) {
   icon_->SetImage(icon);
 }