Android : Add and remove WebView from FrameLayout in Fragment dynamically causes memory leak (Grow heap (frag case))

I am so sorry if this is duplicate question, I googled for 1 day but still not find the desired solution. Because I want to preserve all state of WebView (javascript environment, display pages...), I declare my webview in application class as below

public class RAPINaviMainApplication extends Application {
    private WebView mWebView = null;
    private boolean isWebViewInitialized = false;


    @Override
    public void onCreate () {
        super.onCreate();
        mWebView = new WebView(getApplicationContext());
        isWebViewInitialized = false; // we do some initialization once in our activity.
        mWebView.setWebViewClient(new WebViewClient());
        mWebView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        mWebView.getSettings().setJavaScriptEnabled(true);

    }

    public boolean isWebViewInitialized() {
        return isWebViewInitialized;
    }

    public void setWebViewInitialized(boolean initialize) {
        isWebViewInitialized = initialize;
    }

    public WebView getWebView() {
        return mWebView;
    }   

}

And then I add webview in a RAPINaviMainFragment dynamically to display its content when user choose the fragment in Naviagtion Drawer (Android Navigation Drawer template) as below

public class RAPINaviMainFragment extends Fragment {

    private static final String ARG_SECTION_NUMBER = "section_number";
    private static final String TAG = "RAPINaviMainFragment";
    private FrameLayout mFrameLayout;



    public static RAPINaviMainFragment newInstance(int sectionNumber) {
        RAPINaviMainFragment fragment = new RAPINaviMainFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        fragment.setArguments(args);

        return fragment;
    }

    public RAPINaviMainFragment() {
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_rapinavi_main, container,
                false);
        mFrameLayout = (FrameLayout) rootView.findViewById(R.id.webview_container);


        if (((RAPINaviMainApplication)getActivity().getApplication()).isWebViewInitialized() == false) {
            ((RAPINaviMainApplication)getActivity().getApplication()).getWebView().loadUrl("http://www.google.com");
            ((RAPINaviMainApplication)getActivity().getApplication()).setWebViewInitialized(true);
        }       


        return rootView;
    }

    @Override
    public void onAttach(Activity activity) {
        Log.i(TAG, getClass().getSimpleName() + ":entered onAttach()");
        super.onAttach(activity);
        ((RAPINaviMainActivity) activity).onSectionAttached(getArguments()
                .getInt(ARG_SECTION_NUMBER));
    }


    @Override
    public void onResume() {
        Log.i(TAG, getClass().getSimpleName() + ":entered onResume()");
        super.onResume();
        mFrameLayout.addView(((RAPINaviMainApplication)getActivity().getApplication()).getWebView()); 
    }

    @Override
    public void onPause() {
        Log.i(TAG, getClass().getSimpleName() + ":entered onPause()");
        super.onPause();
        mFrameLayout.removeView(((RAPINaviMainApplication)getActivity().getApplication()).getWebView());
    }
}

The problem is that, whenver user switch from other Fragment to RAPINaviMainFragment (by selecting item in Naviation Drawer) or when user load a new website in webview, I receive the memory leak information from logcat

07-26 14:11:31.371: I/dalvikvm-heap(10391): Grow heap (frag case) to 12.937MB for 6317296-byte allocation
07-26 14:11:34.825: I/RAPINaviMainFragment(10391): RAPINaviMainFragment:entered onPause()
07-26 14:11:37.578: I/RAPINaviMainFragment(10391): RAPINaviMainFragment:entered onAttach()
07-26 14:11:37.578: I/RAPINaviMainFragment(10391): RAPINaviMainFragment:entered onResume()
07-26 14:11:37.618: I/dalvikvm-heap(10391): Grow heap (frag case) to 12.936MB for 6317296-byte allocation
07-26 14:12:42.167: I/RAPINaviMainFragment(10391): RAPINaviMainFragment:entered onPause()

I also set follow option in AndroidManifest.xml

  android:largeHeap="true"

When I commented addView() and removeView() action from FrameLayout, there was no memory leak. I also tried to use WeakReference to WebView RAPINaviApplication but the issue still occurs. I am really appreciate if anyone know the root of this problem and give me the solution to solve it.