Use selectableItemBackground for material prefs

RecyclerView doesn't draw the ripple for us like ListView does.

b/23901977

Change-Id: I9cfbf154c18d7165fe6ce9e26cd79d414d9ba0f6
diff --git a/v14/preference/res/layout-v17/preference_material.xml b/v14/preference/res/layout-v17/preference_material.xml
index e624773..f907d2f 100644
--- a/v14/preference/res/layout-v17/preference_material.xml
+++ b/v14/preference/res/layout-v17/preference_material.xml
@@ -23,7 +23,7 @@
     android:gravity="center_vertical"
     android:paddingStart="?android:attr/listPreferredItemPaddingStart"
     android:paddingEnd="?android:attr/listPreferredItemPaddingEnd"
-    android:background="?android:attr/activatedBackgroundIndicator"
+    android:background="?android:attr/selectableItemBackground"
     android:clipToPadding="false"
     android:focusable="true" >
 
diff --git a/v14/preference/res/layout-v21/preference_material.xml b/v14/preference/res/layout-v21/preference_material.xml
index 392a2ea..da6b69f 100644
--- a/v14/preference/res/layout-v21/preference_material.xml
+++ b/v14/preference/res/layout-v21/preference_material.xml
@@ -23,7 +23,7 @@
     android:gravity="center_vertical"
     android:paddingStart="?android:attr/listPreferredItemPaddingStart"
     android:paddingEnd="?android:attr/listPreferredItemPaddingEnd"
-    android:background="?android:attr/activatedBackgroundIndicator"
+    android:background="?android:attr/selectableItemBackground"
     android:clipToPadding="false"
     android:focusable="true" >
 
diff --git a/v14/preference/res/layout/preference_material.xml b/v14/preference/res/layout/preference_material.xml
index 6135053..bb483c8 100644
--- a/v14/preference/res/layout/preference_material.xml
+++ b/v14/preference/res/layout/preference_material.xml
@@ -23,7 +23,7 @@
     android:gravity="center_vertical"
     android:paddingLeft="?android:attr/listPreferredItemPaddingLeft"
     android:paddingRight="?android:attr/listPreferredItemPaddingRight"
-    android:background="?android:attr/activatedBackgroundIndicator"
+    android:background="?android:attr/selectableItemBackground"
     android:clipToPadding="false"
     android:focusable="true" >