Allow testing of signal strength

- Let any process with NETWORK_SETTINGS register for signal strength
  wakeup.
- Allow agents registering test networks to assign them a signal
  strength.

Test: NetworkAgentTest
Bug: 139268426
Change-Id: I2b4b89be3e69f4853fd6978d2c8f5c8eb4271f21

core/java/android/net/NetworkCapabilities.java

@@ -669,11 +669,13 @@ public final class NetworkCapabilities implements Parcelable {
     public void restrictCapabilitesForTestNetwork() {
         final long originalCapabilities = mNetworkCapabilities;
         final NetworkSpecifier originalSpecifier = mNetworkSpecifier;
+        final int originalSignalStrength = mSignalStrength;
         clearAll();
         // Reset the transports to only contain TRANSPORT_TEST.
         mTransportTypes = (1 << TRANSPORT_TEST);
         mNetworkCapabilities = originalCapabilities & TEST_NETWORKS_ALLOWED_CAPABILITIES;
         mNetworkSpecifier = originalSpecifier;
+        mSignalStrength = originalSignalStrength;
     }
 
     /**

services/core/java/com/android/server/ConnectivityService.java

@@ -2142,7 +2142,8 @@ public class ConnectivityService extends IConnectivityManager.Stub
     private boolean checkNetworkSignalStrengthWakeupPermission(int pid, int uid) {
         return checkAnyPermissionOf(pid, uid,
                 android.Manifest.permission.NETWORK_SIGNAL_STRENGTH_WAKEUP,
-                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK,
+                android.Manifest.permission.NETWORK_SETTINGS);
     }
 
     private void enforceConnectivityRestrictedNetworksPermission() {