Add default calls/SMS subscription prefs to mobile details page

This adds prefs to the the details page for mobile network subscriptions
that appear in multi-SIM mode. They show which subscription is set as
the default for calls and SMS respectively, and let the user change what
the default is for each. They can be set to either a specific
subscription, or set to "Ask every time".

Bug: 122670283
Test: make RunSettingsRoboTests
Change-Id: Id2b23e4b5c3d1b5c04b5766e73fc8202c05d8f75

src/com/android/settings/network/telephony/SmsDefaultSubscriptionController.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2019 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.telephony;
+
+import android.content.Context;
+import android.telephony.SubscriptionInfo;
+import android.telephony.SubscriptionManager;
+
+public class SmsDefaultSubscriptionController extends DefaultSubscriptionController {
+
+    public SmsDefaultSubscriptionController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+    }
+
+    @Override
+    protected SubscriptionInfo getDefaultSubscriptionInfo() {
+        return mManager.getDefaultSmsSubscriptionInfo();
+    }
+
+    @Override
+    protected int getDefaultSubscriptionId() {
+        return SubscriptionManager.getDefaultSmsSubscriptionId();
+    }
+
+    @Override
+    protected void setDefaultSubscription(int subscriptionId) {
+        mManager.setDefaultSmsSubId(subscriptionId);
+    }
+}