[Provider Model] Fix Internet preference crash

- Post on main thread for UI update

- Add NPE checking

Bug: 178670562
Test: manual test
- atest InternetPreferenceControllerTest

Change-Id: I6c37f7dc19f9f9bbc75b36415a47aa1366dc5f5e

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

@@ -31,6 +31,7 @@ import android.telephony.SubscriptionInfo;
 import android.telephony.SubscriptionManager;
 
 import androidx.annotation.IdRes;
+import androidx.annotation.VisibleForTesting;
 import androidx.lifecycle.Lifecycle;
 import androidx.lifecycle.LifecycleObserver;
 import androidx.lifecycle.OnLifecycleEvent;
@@ -42,6 +43,7 @@ import com.android.settings.widget.SummaryUpdater;
 import com.android.settings.wifi.WifiSummaryUpdater;
 import com.android.settingslib.Utils;
 import com.android.settingslib.core.AbstractPreferenceController;
+import com.android.settingslib.utils.ThreadUtils;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -147,8 +149,13 @@ public class InternetPreferenceController extends AbstractPreferenceController i
      * @param internetType the internet type
      */
     public void onInternetTypeChanged(@InternetUpdater.InternetType int internetType) {
+        final boolean needUpdate = (internetType != mInternetType);
         mInternetType = internetType;
+        if (needUpdate) {
+            ThreadUtils.postOnMainThread(() -> {
                 updateState(mPreference);
+            });
+        }
     }
 
     @Override
@@ -158,13 +165,17 @@ public class InternetPreferenceController extends AbstractPreferenceController i
         }
     }
 
-    private void updateCellularSummary() {
+    @VisibleForTesting
+    void updateCellularSummary() {
         final SubscriptionManager subscriptionManager =
                 mContext.getSystemService(SubscriptionManager.class);
         if (subscriptionManager == null) {
             return;
         }
         SubscriptionInfo subInfo = subscriptionManager.getDefaultDataSubscriptionInfo();
+        if (subInfo == null) {
+            return;
+        }
         mPreference.setSummary(subInfo.getDisplayName());
     }
 }

tests/unit/src/com/android/settings/network/InternetPreferenceControllerTest.java

@@ -36,6 +36,7 @@ import android.net.NetworkScoreManager;
 import android.net.wifi.WifiManager;
 import android.os.Handler;
 import android.os.Looper;
+import android.telephony.SubscriptionManager;
 
 import androidx.lifecycle.Lifecycle;
 import androidx.preference.Preference;
@@ -123,4 +124,13 @@ public class InternetPreferenceControllerTest {
 
         assertThat(mPreference.getSummary()).isEqualTo(TEST_SUMMARY);
     }
+
+    @Test
+    public void updateCellularSummary_getNullSubscriptionInfo_shouldNotCrash() {
+        final SubscriptionManager subscriptionManager = mock(SubscriptionManager.class);
+        when(mContext.getSystemService(SubscriptionManager.class)).thenReturn(subscriptionManager);
+        when(subscriptionManager.getDefaultDataSubscriptionInfo()).thenReturn(null);
+
+        mController.updateCellularSummary();
+    }
 }