Fix bug about Wi-Fi dialog rotation

When user clicks a Wi-Fi access point in WifiSettings,
screen pops up a Wi-Fi point dialog. And then user
rotates the screen, Wi-Fi access dialog changes to
"Add network" full screen dialog.

In old code, we check whether dialog is showing by
dialog.isShowing() in onSaveInstanceState.
For now, this design is not appropriate. Since isShowing()
won't return true anymore when fragment calls onSaveInstanceState.

So, we check dialog object whether is null or not now.
If dialog is null, it means that there is no dialog was shown,
before user rotates the screen.

Change-Id: I7dc26369c005f576fe679abc70327f6a02620935
Fixes: 112624846
Test: manual test, robo test

src/com/android/settings/wifi/WifiSettings.java

@@ -24,6 +24,7 @@ import android.app.Activity;
 import android.app.Dialog;
 import android.content.ContentResolver;
 import android.content.Context;
+import android.content.DialogInterface;
 import android.content.Intent;
 import android.content.res.Resources;
 import android.net.ConnectivityManager;
@@ -87,7 +88,7 @@ import java.util.List;
 @SearchIndexable
 public class WifiSettings extends RestrictedSettingsFragment
         implements Indexable, WifiTracker.WifiListener, AccessPointListener,
-        WifiDialog.WifiDialogListener {
+        WifiDialog.WifiDialogListener, DialogInterface.OnDismissListener {
 
     private static final String TAG = "WifiSettings";
 
@@ -432,9 +433,8 @@ public class WifiSettings extends RestrictedSettingsFragment
     @Override
     public void onSaveInstanceState(Bundle outState) {
         super.onSaveInstanceState(outState);
-
+        // If dialog has been shown, save its state.
-        // If the dialog is showing, save its state.
+        if (mDialog != null) {
-        if (mDialog != null && mDialog.isShowing()) {
             outState.putInt(SAVE_DIALOG_MODE, mDialogMode);
             if (mDlgAccessPoint != null) {
                 mAccessPointSavedState = new Bundle();
@@ -623,6 +623,18 @@ public class WifiSettings extends RestrictedSettingsFragment
         return super.onCreateDialog(dialogId);
     }
 
+    @Override
+    public void onDialogShowing() {
+        super.onDialogShowing();
+        setOnDismissListener(this);
+    }
+
+    @Override
+    public void onDismiss(DialogInterface dialog) {
+        // We don't keep any dialog object when dialog was dismissed.
+        mDialog = null;
+    }
+
     @Override
     public int getDialogMetricsCategory(int dialogId) {
         switch (dialogId) {