Add data saver to settings

Bug: 22817899

Change-Id: Ic3055aa6a5baae1653db350313366f180c049cc7

src/com/android/settings/datausage/DataSaverPreference.java

@@ -0,0 +1,47 @@
+/*
+ * 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.datausage;
+
+import android.content.Context;
+import android.support.v7.preference.Preference;
+import android.util.AttributeSet;
+import com.android.settings.R;
+
+public class DataSaverPreference extends Preference implements DataSaverBackend.Listener {
+
+    private final DataSaverBackend mDataSaverBackend;
+
+    public DataSaverPreference(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        mDataSaverBackend = new DataSaverBackend(context);
+    }
+
+    @Override
+    public void onAttached() {
+        super.onAttached();
+        mDataSaverBackend.addListener(this);
+    }
+
+    @Override
+    public void onDetached() {
+        super.onDetached();
+        mDataSaverBackend.addListener(this);
+    }
+
+    @Override
+    public void onDataSaverChanged(boolean isDataSaving) {
+        setSummary(isDataSaving ? R.string.data_saver_on : R.string.data_saver_off);
+    }
+}