Fix Wi-Fi SSID null handling

When Wi-Fi SSID is null in NetworkCapabilities,
get Wi-Fi SSID from connection info (WifiInfo) which is non-null design.

Bug: 176396812
Test: FrameworksNetTests NetworkPolicyManagerServiceTest
Change-Id: I59c7d8f7e176d0c6bb100721269f3f6165f0ca21
diff --git a/core/java/android/net/NetworkIdentity.java b/core/java/android/net/NetworkIdentity.java
index b037261..1eef7d9 100644
--- a/core/java/android/net/NetworkIdentity.java
+++ b/core/java/android/net/NetworkIdentity.java
@@ -198,15 +198,11 @@
         final int oemManaged = getOemBitfield(snapshot.networkCapabilities);
 
         if (legacyType == TYPE_WIFI) {
-            if (snapshot.networkCapabilities.getSsid() != null) {
-                networkId = snapshot.networkCapabilities.getSsid();
-                if (networkId == null) {
-                    // TODO: Figure out if this code path never runs. If so, remove them.
-                    final WifiManager wifi = (WifiManager) context.getSystemService(
-                            Context.WIFI_SERVICE);
-                    final WifiInfo info = wifi.getConnectionInfo();
-                    networkId = info != null ? info.getSSID() : null;
-                }
+            networkId = snapshot.networkCapabilities.getSsid();
+            if (networkId == null) {
+                final WifiManager wifi = context.getSystemService(WifiManager.class);
+                final WifiInfo info = wifi.getConnectionInfo();
+                networkId = info != null ? info.getSSID() : null;
             }
         }