add correct background to tab switcher

    Bug: 5075753

Change-Id: I1c03f6c8c43ec78b888b1756d5937858bd612e78
diff --git a/res/layout/nav_screen.xml b/res/layout/nav_screen.xml
index 4e00fa3..4c74991 100644
--- a/res/layout/nav_screen.xml
+++ b/res/layout/nav_screen.xml
@@ -20,7 +20,7 @@
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical"
-    android:background="@drawable/nav_screen_bg">
+    android:background="@drawable/browser_background_holo">
     <com.android.browser.NavTabGallery
         android:id="@+id/scroller"
         android:layout_width="match_parent"