Remove usage of Context.NETWORK_STACK_SERVICE

The NetworkStack.getService() API should be used instead.

Bug: 151243982
Test: atest FrameworksNetTests TetheringTests
      Manual tethering test
Change-Id: I7855090bffbe895c8349ad4903b8f2eb55515f0b
diff --git a/packages/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java b/packages/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
index 020b32a..c5329d8 100644
--- a/packages/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
+++ b/packages/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
@@ -33,6 +33,7 @@
 import android.net.ITetheringEventCallback;
 import android.net.NetworkCapabilities;
 import android.net.NetworkRequest;
+import android.net.NetworkStack;
 import android.net.TetheringRequestParcel;
 import android.net.dhcp.DhcpServerCallbacks;
 import android.net.dhcp.DhcpServingParamsParcel;
@@ -364,8 +365,7 @@
                     IBinder connector;
                     try {
                         final long before = System.currentTimeMillis();
-                        while ((connector = (IBinder) mContext.getSystemService(
-                                Context.NETWORK_STACK_SERVICE)) == null) {
+                        while ((connector = NetworkStack.getService()) == null) {
                             if (System.currentTimeMillis() - before > NETWORKSTACK_TIMEOUT_MS) {
                                 Log.wtf(TAG, "Timeout, fail to get INetworkStackConnector");
                                 return null;
diff --git a/tests/net/java/com/android/server/ConnectivityServiceTest.java b/tests/net/java/com/android/server/ConnectivityServiceTest.java
index 8c0c36b..5c5e225 100644
--- a/tests/net/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/net/java/com/android/server/ConnectivityServiceTest.java
@@ -428,7 +428,6 @@
         public Object getSystemService(String name) {
             if (Context.CONNECTIVITY_SERVICE.equals(name)) return mCm;
             if (Context.NOTIFICATION_SERVICE.equals(name)) return mNotificationManager;
-            if (Context.NETWORK_STACK_SERVICE.equals(name)) return mNetworkStack;
             if (Context.USER_SERVICE.equals(name)) return mUserManager;
             if (Context.ALARM_SERVICE.equals(name)) return mAlarmManager;
             if (Context.LOCATION_SERVICE.equals(name)) return mLocationManager;