Add 'Adaptive connectivity' UI

'Adaptive connectivity' toggle button controls whether
network connection is automatically managed.

Bug: 162871294
Test: make RunSettingsRoboTests
      manual
      Switch the toggle button and reboot device, observe
      if the state is retained.
Change-Id: I4499a3639abab356e8faa6316bfa45541efd63ac

src/com/android/settings/network/AdaptiveConnectivitySettings.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2020 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.network;
+
+import android.app.settings.SettingsEnums;
+
+import com.android.settings.R;
+import com.android.settings.dashboard.DashboardFragment;
+import com.android.settings.search.BaseSearchIndexProvider;
+import com.android.settingslib.search.SearchIndexable;
+
+/**
+ * Adaptive connectivity is a feature which automatically manages network connections.
+ */
+@SearchIndexable
+public class AdaptiveConnectivitySettings extends DashboardFragment {
+
+    private static final String TAG = "AdaptiveConnectivitySettings";
+
+    private static final String KEY_ADAPTIVE_CONNECTIVITY_PREFERENCE = "adaptive_connectivity";
+
+    @Override
+    public int getMetricsCategory() {
+        return SettingsEnums.ADAPTIVE_CONNECTIVITY_CATEGORY;
+    }
+
+    @Override
+    protected String getLogTag() {
+        return TAG;
+    }
+
+    @Override
+    protected int getPreferenceScreenResId() {
+        return R.xml.adaptive_connectivity_settings;
+    }
+
+    public static final BaseSearchIndexProvider SEARCH_INDEX_DATA_PROVIDER =
+            new BaseSearchIndexProvider(R.xml.adaptive_connectivity_settings);
+}