Fix up NetworkCapabilities' toString

Test: manual
Change-Id: I3bcec6a6873e8ec7ced0820d3d5b92249b19fe0a

core/java/android/net/UidRange.java

@@ -21,8 +21,6 @@ import static android.os.UserHandle.PER_USER_RANGE;
 import android.os.Parcel;
 import android.os.Parcelable;
 
-import java.lang.IllegalArgumentException;
-
 /**
  * An inclusive range of UIDs.
  *
@@ -52,6 +50,13 @@ public final class UidRange implements Parcelable {
         return start <= uid && uid <= stop;
     }
 
+    /**
+     * Returns the count of UIDs in this range.
+     */
+    public int count() {
+        return 1 + stop - start;
+    }
+
     /**
      * @return {@code true} if this range contains every UID contained by the {@param other} range.
      */