Make EnabledNetworkModePreferenceController listen to setting changes

The controller for the "Preferred network type" preference on the SIM
details page wasn't listening for changes to the underlying global
setting, so changes to the setting would be reflected in SysUI but not
on this page if it happened to be showing.

Bug: 135667565
Test: make RunSettingsRoboTests
Change-Id: I5dfe4843a681c613f49caf4584e9dbebc54e708a

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

@@ -16,7 +16,13 @@
 
 package com.android.settings.network.telephony;
 
+import static androidx.lifecycle.Lifecycle.Event.ON_START;
+import static androidx.lifecycle.Lifecycle.Event.ON_STOP;
+
 import android.content.Context;
+import android.database.ContentObserver;
+import android.os.Handler;
+import android.os.Looper;
 import android.os.PersistableBundle;
 import android.provider.Settings;
 import android.telephony.CarrierConfigManager;
@@ -25,8 +31,12 @@ import android.telephony.SubscriptionManager;
 import android.telephony.TelephonyManager;
 
 import androidx.annotation.VisibleForTesting;
+import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.LifecycleObserver;
+import androidx.lifecycle.OnLifecycleEvent;
 import androidx.preference.ListPreference;
 import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
 
 import com.android.internal.telephony.Phone;
 import com.android.internal.telephony.PhoneConstants;
@@ -37,17 +47,27 @@ import com.android.settings.R;
  */
 public class EnabledNetworkModePreferenceController extends
         TelephonyBasePreferenceController implements
-        ListPreference.OnPreferenceChangeListener {
+        ListPreference.OnPreferenceChangeListener, LifecycleObserver {
 
     private CarrierConfigManager mCarrierConfigManager;
+    private ContentObserver mPreferredNetworkModeObserver;
     private TelephonyManager mTelephonyManager;
     private boolean mIsGlobalCdma;
     @VisibleForTesting
     boolean mShow4GForLTE;
+    private Preference mPreference;
 
     public EnabledNetworkModePreferenceController(Context context, String key) {
         super(context, key);
         mCarrierConfigManager = context.getSystemService(CarrierConfigManager.class);
+        mPreferredNetworkModeObserver = new ContentObserver(new Handler(Looper.getMainLooper())) {
+            @Override
+            public void onChange(boolean selfChange) {
+                if (mPreference != null) {
+                    updateState(mPreference);
+                }
+            }
+        };
     }
 
     @Override
@@ -78,6 +98,24 @@ public class EnabledNetworkModePreferenceController extends
         return visible ? AVAILABLE : CONDITIONALLY_UNAVAILABLE;
     }
 
+    @OnLifecycleEvent(ON_START)
+    public void onStart() {
+        mContext.getContentResolver().registerContentObserver(
+                Settings.Global.getUriFor(Settings.Global.PREFERRED_NETWORK_MODE + mSubId), true,
+                mPreferredNetworkModeObserver);
+    }
+
+    @OnLifecycleEvent(ON_STOP)
+    public void onStop() {
+        mContext.getContentResolver().unregisterContentObserver(mPreferredNetworkModeObserver);
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        mPreference = screen.findPreference(getPreferenceKey());
+    }
+
     @Override
     public void updateState(Preference preference) {
         super.updateState(preference);
@@ -102,7 +140,7 @@ public class EnabledNetworkModePreferenceController extends
         return false;
     }
 
-    public void init(int subId) {
+    public void init(Lifecycle lifecycle, int subId) {
         mSubId = subId;
         final PersistableBundle carrierConfig = mCarrierConfigManager.getConfigForSubId(mSubId);
         mTelephonyManager = TelephonyManager.from(mContext).createForSubscriptionId(mSubId);
@@ -115,6 +153,7 @@ public class EnabledNetworkModePreferenceController extends
                 ? carrierConfig.getBoolean(
                 CarrierConfigManager.KEY_SHOW_4G_FOR_LTE_DATA_ICON_BOOL)
                 : false;
+        lifecycle.addObserver(this);
     }
 
     private int getPreferredNetworkMode() {

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

@@ -150,7 +150,7 @@ public class MobileNetworkSettings extends RestrictedDashboardFragment {
         use(CarrierPreferenceController.class).init(mSubId);
         use(DataUsagePreferenceController.class).init(mSubId);
         use(PreferredNetworkModePreferenceController.class).init(mSubId);
-        use(EnabledNetworkModePreferenceController.class).init(mSubId);
+        use(EnabledNetworkModePreferenceController.class).init(getLifecycle(), mSubId);
         use(DataServiceSetupPreferenceController.class).init(mSubId);
         if (!FeatureFlagPersistent.isEnabled(getContext(), FeatureFlags.NETWORK_INTERNET_V2)) {
             use(EuiccPreferenceController.class).init(mSubId);