Add mms preference and controller

Only visible when it is metered and mobile data off.
Also refactor one mobile data observer so we can reuse it.

Bug: 130222866
Test: RunSettingsRoboTests
Change-Id: Id218f51da3c373fad98c1a39cfadd6b0e8c46a88

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

@@ -0,0 +1,106 @@
+/*
+ * 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.os.Handler;
+import android.os.Looper;
+import android.telephony.SubscriptionManager;
+import android.telephony.TelephonyManager;
+import android.telephony.data.ApnSetting;
+import android.util.Log;
+
+import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
+import androidx.preference.SwitchPreference;
+
+import com.android.settings.network.MobileDataContentObserver;
+import com.android.settingslib.core.lifecycle.LifecycleObserver;
+import com.android.settingslib.core.lifecycle.events.OnStart;
+import com.android.settingslib.core.lifecycle.events.OnStop;
+
+/**
+ * Preference controller for "Mobile data"
+ */
+public class MmsMessagePreferenceController extends TelephonyTogglePreferenceController implements
+        LifecycleObserver, OnStart, OnStop {
+    private TelephonyManager mTelephonyManager;
+    private SubscriptionManager mSubscriptionManager;
+    private MobileDataContentObserver mMobileDataContentObserver;
+    private SwitchPreference mPreference;
+
+    public MmsMessagePreferenceController(Context context, String key) {
+        super(context, key);
+        mSubscriptionManager = context.getSystemService(SubscriptionManager.class);
+        mMobileDataContentObserver = new MobileDataContentObserver(
+                new Handler(Looper.getMainLooper()));
+        mMobileDataContentObserver.setOnMobileDataChangedListener(()->updateState(mPreference));
+    }
+
+    @Override
+    public int getAvailabilityStatus(int subId) {
+        final TelephonyManager telephonyManager = TelephonyManager
+                .from(mContext).createForSubscriptionId(subId);
+        return (subId != SubscriptionManager.INVALID_SUBSCRIPTION_ID
+                && !telephonyManager.isDataEnabled()
+                && telephonyManager.isApnMetered(ApnSetting.TYPE_MMS))
+                ? AVAILABLE
+                : CONDITIONALLY_UNAVAILABLE;
+    }
+
+    @Override
+    public void onStart() {
+        if (mSubId != SubscriptionManager.INVALID_SUBSCRIPTION_ID) {
+            mMobileDataContentObserver.register(mContext, mSubId);
+        }
+    }
+
+    @Override
+    public void onStop() {
+        if (mSubId != SubscriptionManager.INVALID_SUBSCRIPTION_ID) {
+            mMobileDataContentObserver.unRegister(mContext);
+        }
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        mPreference = screen.findPreference(getPreferenceKey());
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        super.updateState(preference);
+        preference.setVisible(isAvailable());
+        ((SwitchPreference) preference).setChecked(isChecked());
+    }
+
+    public void init(int subId) {
+        mSubId = subId;
+        mTelephonyManager = TelephonyManager.from(mContext).createForSubscriptionId(mSubId);
+    }
+
+    @Override
+    public boolean setChecked(boolean isChecked) {
+        return mSubscriptionManager.setAlwaysAllowMmsData(mSubId, isChecked);
+    }
+
+    @Override
+    public boolean isChecked() {
+        return mTelephonyManager.isDataEnabledForApn(ApnSetting.TYPE_MMS);
+    }
+}