Don't draw divider under headers

Create SettingsDividerItemDecoration which reads PreferenceViewHolder
isDividerAllowedAbove/Below so that will be taken into account as
well as other ViewHolders which implements DividedViewHolder.

Bug: 28445348
Change-Id: I73e298f2ca1688b135e533a8d3ef5f5c154963f7

src/com/android/settings/SetupChooseLockGeneric.java

@@ -34,6 +34,7 @@ import android.widget.LinearLayout;
 
 import com.android.internal.widget.LockPatternUtils;
 import com.android.settings.fingerprint.SetupSkipDialog;
+import com.android.settings.utils.SettingsDividerItemDecoration;
 import com.android.setupwizardlib.GlifPreferenceLayout;
 
 /**
@@ -79,6 +80,7 @@ public class SetupChooseLockGeneric extends ChooseLockGeneric {
             super.onViewCreated(view, savedInstanceState);
 
             GlifPreferenceLayout layout = (GlifPreferenceLayout) view;
+            layout.setDividerItemDecoration(new SettingsDividerItemDecoration(getContext()));
             layout.setDividerInset(getContext().getResources().getDimensionPixelSize(
                     R.dimen.suw_items_glif_text_divider_inset));
 

src/com/android/settings/SetupEncryptionInterstitial.java

@@ -27,6 +27,7 @@ import android.view.ViewGroup;
 import android.widget.LinearLayout;
 import android.widget.TextView;
 
+import com.android.settings.utils.SettingsDividerItemDecoration;
 import com.android.setupwizardlib.GlifPreferenceLayout;
 
 /**
@@ -81,6 +82,7 @@ public class SetupEncryptionInterstitial extends EncryptionInterstitial {
             super.onViewCreated(view, savedInstanceState);
 
             final GlifPreferenceLayout layout = (GlifPreferenceLayout) view;
+            layout.setDividerItemDecoration(new SettingsDividerItemDecoration(getContext()));
             layout.setDividerInset(getContext().getResources().getDimensionPixelSize(
                     R.dimen.suw_items_glif_icon_divider_inset));
             layout.setIcon(getContext().getDrawable(R.drawable.ic_lock));

src/com/android/settings/utils/SettingsDividerItemDecoration.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.utils;
+
+import android.content.Context;
+import android.support.v7.preference.PreferenceViewHolder;
+import android.support.v7.widget.RecyclerView;
+
+import com.android.setupwizardlib.DividerItemDecoration;
+
+public class SettingsDividerItemDecoration extends DividerItemDecoration {
+
+    public SettingsDividerItemDecoration(Context context) {
+        super(context);
+    }
+
+    @Override
+    protected boolean isDividerAllowedAbove(RecyclerView.ViewHolder viewHolder) {
+        if (viewHolder instanceof PreferenceViewHolder) {
+            return ((PreferenceViewHolder) viewHolder).isDividerAllowedAbove();
+        }
+        return super.isDividerAllowedAbove(viewHolder);
+    }
+
+    @Override
+    protected boolean isDividerAllowedBelow(RecyclerView.ViewHolder viewHolder) {
+        if (viewHolder instanceof PreferenceViewHolder) {
+            return ((PreferenceViewHolder) viewHolder).isDividerAllowedBelow();
+        }
+        return super.isDividerAllowedBelow(viewHolder);
+    }
+}