Android WebChromeClient onCloseWindow not working

I have a simple android app that opens a webview to call a web application.
I want to close the entire android app when the web application has a window.close();

I also want the back key to navigate back through the web pages, and that is working.

The window is closing, but the application is not closing and the log is not being updated. I think the onWindowClose is not being triggered for some reason.

This is my android app -

import java.util.HashMap;
import java.util.Map;

import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.KeyEvent;

import android.os.Bundle;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.webkit.WebViewClient;
public class MainActivity extends Activity {

protected static final String TAG = null;
private WebView webView;


@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if(event.getAction() == KeyEvent.ACTION_DOWN){
        switch(keyCode)
        {
        case KeyEvent.KEYCODE_BACK:
            if(webView.canGoBack()){
                webView.goBack();
            }else{
                finish();
            }
            return true;
        }

    }
    return super.onKeyDown(keyCode, event);
}

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Map<String,String> extraHeaders = new HashMap<String, String>();
    extraHeaders.put("X-Requested-With", "MY-App");


    //webview use to call own site
    webView = (WebView) findViewById(R.id.webView1);
    webView.setWebViewClient(new WebViewClient()); //use to hide the address bar      
    webView .getSettings().setJavaScriptEnabled(true);     
    webView .getSettings().setJavaScriptCanOpenWindowsAutomatically(true);
    webView .getSettings().setDomStorageEnabled(true); //to store history  
    webView.setWebViewClient(new WebViewClient()); 
    webView.loadUrl("http://www.Google.com",extraHeaders); 

    WebChromeClient wbc = new WebChromeClient(){


        public void onCloseWindow(WebView webView){
            super.onCloseWindow(webView);

            Log.d(TAG, "Window trying to close");
            Intent intent = new Intent(getApplicationContext(), MainActivity.class);
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
            startActivity(intent);
            finish();

        }

  };


  webView.setWebChromeClient(wbc);

 ;


 } 

Here is the Manifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.google"
android:versionCode="1"
android:versionName="1.0" 
<uses-sdk
  android:minSdkVersion="8"
  android:targetSdkVersion="16" />

<uses-permission android:name="android.permission.INTERNET" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/Google"
    android:theme="@style/AppTheme" 
    android:noHistory="true"
    android:excludeFromRecents="true"
     >

    <activity
        android:name="com.example.google.MainActivity"
        android:label="@string/app_name" 
        android:clearTaskOnLaunch="true"
        android:configChanges="orientation|keyboard|keyboardHidden|screenSize">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
  </activity>
  </application>

</manifest>'

Thanks for all your help!

OK. I did some research and discovered that window.close() is disabled by some browsers. I really just want to close the app when people log out of the website.

In website php for logging out I added this.

// return to main page

  header('Location: https://www.mainpage.com/');

Then I changed my MainActivity.Java to this:

package com.example.mainpage;

import java.util.HashMap;
import java.util.Map;

import android.app.Activity;
import android.util.Log;
import android.view.KeyEvent;


import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends Activity {

    protected static final String TAG = null;
    private WebView webView;


    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if(event.getAction() == KeyEvent.ACTION_DOWN){
            switch(keyCode)
            {
            case KeyEvent.KEYCODE_BACK:
                if(webView.canGoBack()){
              //    Log.d(TAG, "Before Go Back");
                    webView.goBack();
                }else{
               //   Log.d(TAG, "Before Finish");
                    finish();
                }
                return true;
            }
        }
        return super.onKeyDown(keyCode, event);
    }

    public class MyWebViewClient extends WebViewClient {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            if (url.equals("https://www.mainpage.com/")) {
            //  Log.d(TAG, "Override");
            //  Log.d("TAG", url);
            //  Log.d(TAG, "Logging Out");
            //  Log.d(TAG, "Before Finish");
              finish();
              return true;
            }
            else {
            // Otherwise, give the default behavior (open in browser)
            //Log.d(TAG, "Do Not Override");
            //Log.d("TAG", url);
           // Log.d(TAG, "loading page");
            return false;
            }
        }

    }

public void onCreate(Bundle savedInstanceState) {

    Log.d(TAG, "In On Create");
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Map<String,String> extraHeaders = new HashMap<String, String>();
    extraHeaders.put("X-Requested-With", "MY-App");

    webView = (WebView) findViewById(R.id.webView1);
    webView .getSettings().setJavaScriptEnabled(true);     
    webView .getSettings().setJavaScriptCanOpenWindowsAutomatically(true);
    webView .getSettings().setDomStorageEnabled(true); //to store history  
    webView.loadUrl("https://www.mainpage.com/Login.php",extraHeaders);              
    webView.setWebViewClient(new MyWebViewClient());    

  };

}