I want to make fitting the Parent Window to IWebBrowser2 object size

Question

How can I get IWebBrowser2 size ?

I tried the following code. I will get IWebbrowser2 HWND and get client width and apply to Parent Window. What is something wrong ?

    if ( dispIdMember == DISPID_DOCUMENTCOMPLETE) {
        IWebBrowser2* pSite = 0;
        HWND hWnd;
        int nCount = pDispParams->cArgs;
        HRESULT hr = ((IDispatch*)pDispParams->rgvarg[1].pdispVal)->QueryInterface(IID_IWebBrowser2, (void**)&pSite);
        pSite->get_HWND((SHANDLE_PTR *)&hWnd2); hWnd return NULL
                          :
        SetWindowPos(hParentWnd,NULL,0,0,cxNew,cyNew, SWP_NOZORDER | SWP_NOMOVE );
    }