[WifiDialog] Allow adding unspecified AP

In WifiDialogActivity, handle the case where the given
accessPointState is null, and show the Wi-Fi dialog allowing users
to enter the SSID and other credentials. This will be used by setup
wizard when user selected "Add new network" item.

Bug: 23392285
Change-Id: Ica2650d9e829d73281bc9c504c3005d9c5750d31
diff --git a/src/com/android/settings/wifi/WifiDialogActivity.java b/src/com/android/settings/wifi/WifiDialogActivity.java
index 6f9e3d3..9eea98a 100644
--- a/src/com/android/settings/wifi/WifiDialogActivity.java
+++ b/src/com/android/settings/wifi/WifiDialogActivity.java
@@ -43,7 +43,10 @@
 
         final Intent intent = getIntent();
         final Bundle accessPointState = intent.getBundleExtra(KEY_ACCESS_POINT_STATE);
-        final AccessPoint accessPoint = new AccessPoint(this, accessPointState);
+        AccessPoint accessPoint = null;
+        if (accessPointState != null) {
+            accessPoint = new AccessPoint(this, accessPointState);
+        }
 
         WifiDialog dialog = new WifiDialog(this, this, accessPoint, WifiConfigUiBase.MODE_CONNECT);
         dialog.show();