Allow preference theming to remove divider.

Bug: 27962897
Change-Id: I6632f2a3c3d1290c472594f127ad33c9b85023f1
diff --git a/core/java/android/preference/PreferenceFragment.java b/core/java/android/preference/PreferenceFragment.java
index 3e496b6..d4a3582 100644
--- a/core/java/android/preference/PreferenceFragment.java
+++ b/core/java/android/preference/PreferenceFragment.java
@@ -189,12 +189,10 @@
                 0);
 
         ListView lv = (ListView) view.findViewById(android.R.id.list);
-        if (lv != null) {
-            Drawable divider =
-                    a.getDrawable(com.android.internal.R.styleable.PreferenceFragment_divider);
-            if (divider != null) {
-                lv.setDivider(divider);
-            }
+        if (lv != null
+                && a.hasValueOrEmpty(com.android.internal.R.styleable.PreferenceFragment_divider)) {
+            lv.setDivider(
+                    a.getDrawable(com.android.internal.R.styleable.PreferenceFragment_divider));
         }
 
         a.recycle();
diff --git a/core/res/res/values-watch/styles_material.xml b/core/res/res/values-watch/styles_material.xml
index c19cc72..daeeca2 100644
--- a/core/res/res/values-watch/styles_material.xml
+++ b/core/res/res/values-watch/styles_material.xml
@@ -53,6 +53,10 @@
         <item name="wallpaperIntraCloseExitAnimation">@anim/slide_in_exit_micro</item>
     </style>
 
+    <style name="PreferenceFragment.Material" parent="BasePreferenceFragment">
+        <item name="divider">@empty</item>
+    </style>
+
     <style name="Widget.Material.TextView" parent="Widget.TextView">
         <item name="breakStrategy">balanced</item>
     </style>
diff --git a/core/res/res/values/styles_material.xml b/core/res/res/values/styles_material.xml
index 6e0ad36..fad3488 100644
--- a/core/res/res/values/styles_material.xml
+++ b/core/res/res/values/styles_material.xml
@@ -36,7 +36,7 @@
         <item name="layout">@layout/preference_material</item>
     </style>
 
-    <style name="PreferenceFragment.Material">
+    <style name="BasePreferenceFragment">
         <item name="layout">@layout/preference_list_fragment_material</item>
         <item name="paddingStart">@dimen/preference_fragment_padding_side_material</item>
         <item name="paddingEnd">@dimen/preference_fragment_padding_side_material</item>
@@ -46,6 +46,8 @@
         <item name="clipToPadding">@bool/config_preferenceFragmentClipToPadding</item>
     </style>
 
+    <style name="PreferenceFragment.Material" parent="BasePreferenceFragment"/>
+
     <style name="PreferenceActivity.Material">
         <item name="layout">@layout/preference_list_content_material</item>
         <item name="headerLayout">@layout/preference_header_item_material</item>