Extending the shadow effect for search bar to lower devices

> Applying the background to the whole container instead of recycleview

Change-Id: Ifc90d05e0e96c41ba9aaf96b906211b101c2e197
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 2fa16e7..b5acfbd 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -71,6 +71,10 @@
     <dimen name="drop_target_drag_padding">14dp</dimen>
     <dimen name="drop_target_text_size">14sp</dimen>
 
+    <dimen name="all_apps_header_max_elevation">4dp</dimen>
+    <dimen name="all_apps_header_scroll_to_elevation">16dp</dimen>
+    <dimen name="all_apps_header_shadow_height">6dp</dimen>
+
 <!-- Dragging -->
     <!-- the area at the edge of the screen that makes the workspace go left
          or right while you're dragging. -->