Revert "Expose NetworkRegistrationInfo.getNrState() as public API"

getNrState() was exposed. However, it doesn't actually get the NR
state in most cases and it is a mixture of a couple different
concepts. This API does not provide the correct 5G NR state, so
revert it from API surface and also the related change.

Bug: 171183530
Test: make update-api ; m
Change-Id: I651ed14500be5af45dd896ae5da1da36ad249a26

core/api/current.txt

@@ -40607,7 +40607,6 @@ package android.telephony {
     method @NonNull public java.util.List<java.lang.Integer> getAvailableServices();
     method @Nullable public android.telephony.CellIdentity getCellIdentity();
     method public int getDomain();
-    method public int getNrState();
     method @Nullable public String getRegisteredPlmn();
     method public int getTransportType();
     method public boolean isRegistered();

services/core/java/com/android/server/connectivity/DataConnectionStats.java

@@ -52,6 +52,7 @@ public class DataConnectionStats extends BroadcastReceiver {
     private SignalStrength mSignalStrength;
     private ServiceState mServiceState;
     private int mDataState = TelephonyManager.DATA_DISCONNECTED;
+    private int mNrState = NetworkRegistrationInfo.NR_STATE_NONE;
 
     public DataConnectionStats(Context context, Handler listenerHandler) {
         mContext = context;
@@ -99,7 +100,7 @@ public class DataConnectionStats extends BroadcastReceiver {
                 : regInfo.getAccessNetworkTechnology();
         // If the device is in NSA NR connection the networkType will report as LTE.
         // For cell dwell rate metrics, this should report NR instead.
-        if (regInfo != null && regInfo.getNrState() == NetworkRegistrationInfo.NR_STATE_CONNECTED) {
+        if (mNrState == NetworkRegistrationInfo.NR_STATE_CONNECTED) {
             networkType = TelephonyManager.NETWORK_TYPE_NR;
         }
         if (DEBUG) Log.d(TAG, String.format("Noting data connection for network type %s: %svisible",
@@ -171,6 +172,7 @@ public class DataConnectionStats extends BroadcastReceiver {
         @Override
         public void onServiceStateChanged(ServiceState state) {
             mServiceState = state;
+            mNrState = state.getNrState();
             notePhoneDataConnectionState();
         }
 

telephony/java/android/telephony/NetworkRegistrationInfo.java

@@ -371,6 +371,7 @@ public final class NetworkRegistrationInfo implements Parcelable {
      * Get the 5G NR connection state.
      *
      * @return the 5G NR connection state.
+     * @hide
      */
     public @NRState int getNrState() {
         return mNrState;