Merge changes from topic "netstack_api_review" into rvc-dev

* changes:
  Remove usage of Context.NETWORK_STACK_SERVICE
  Remove NETWORK_STACK_SERVICE constant
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java b/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
index 020b32a..c5329d8 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
+++ b/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;