TChromium (dcef3): как правильно сформировать POST запрос

function CreateField(const AValue: AnsiString): ICefPostDataElement;
begin
 Result := TCefPostDataElementRef.New;
 Result.SetToBytes(Length(AValue), PAnsiChar(AValue));
end;
 
//*****************************************
 
procedure POST(total, fee: integer);
var
 Header: ICefStringMultimap;
 Data: ICefPostData;
 Request: ICefRequest;
 Cook: ICefCookieManager;
begin
 Request := TCefRequestRef.New;
 Request.Url := '';
 Request.Method := 'POST';
 Request.Flags:=[UR_FLAG_ALLOW_CACHED_CREDENTIALS,UR_FLAG_ALLOW_COOKIES];
 
 Header := TCefStringMultimapOwn.Create;
 Header.Append('Host', '(...)');
 Header.Append('User-Agent', '(...)');
 Header.Append('Accept', '(...)');
 Header.Append('Accept-Language', '(...)');
 Header.Append('Accept-Encoding', '(...)');
 Header.Append('Content-Type', '(...)');
 Header.Append('Referer', '(...)');
 Header.Append('Content-Length', '(...)');
 Header.Append('Origin', '(...)');
 Header.Append('Connection', '(...)');
 Header.Append('Pragma', '(...)');
 Header.Append('Cache-Control', '(...)');
 
 Header.Append('Cookie',(...));
 ...
 Header.Append('Cookie',(...));
 
 Request.SetHeaderMap(Header);
 
 Data := TCefPostDataRef.New;
 Data.AddElement(CreateField('sessionid='+SessionID));
 Data.AddElement(CreateField('&currency=5'));
 Data.AddElement(CreateField('&subtotal='+inttostr(total-fee)));
 Data.AddElement(CreateField('&fee='+IntToStr(fee)));
 Data.AddElement(CreateField('&total='+IntToStr(total)));
 
 Request.PostData := Data;
 
 form1.Chromium1.Browser.MainFrame.LoadRequest(Request);
end;

var
  PostData: TStringLIst;
  result: String;
begin
  PostData:= TStringList.Create;
  try
    PostData.Add('logon=' + Username);
    PostData.Add('password=' + NASHA_FUNCTION(NASH_PASSWORD));
    HTTP.Request.Accept:= 'bla-bla';
    HTTP.Request.Referer:= HTTP.URL.GetFullURI(); //из предыдущего запроса
    //еще всякое бла-бла
    try
      result:= HTTP.Post('https://www.example.com/users/login.html', PostData);
    except
      //bla-bla
    end;
  finally
    PostData.Free;
  end;

function CreateField(const AValue: AnsiString): ICefPostDataElement;
begin
  Result := TCefPostDataElementRef.New;
  Result.SetToBytes(Length(AValue), PAnsiChar(AValue));
end;
 
//******************************************************************************
procedure POST(total, fee: integer);
var
  Header: ICefStringMultimap;
  Data: ICefPostData;
  Request: ICefRequest;
  Cook: ICefCookieManager;
begin
  Request := TCefRequestRef.New;
  Request.Url := 'https://steamcommunity.com/market/buylisting/'+ ListingID;
  Request.Method := 'POST';
  //Request.Flags := [UR_FLAG_ALLOW_CACHED_CREDENTIALS,UR_FLAG_ALLOW_COOKIES];
  Header := TCefStringMultimapOwn.Create;
  Header.Append('Host', 'steamcommunity.com');
  Header.Append('User-Agent', 'Mozilla/5.0 (Windows NT 5.1; rv:30.0) Gecko/20100101 Firefox/30.0');
  Header.Append('Accept', '*/*');
  Header.Append('Accept-Language', 'ru-RU,ru;q=0.8,en-US;q=0.5,en;q=0.3');
  Header.Append('Accept-Encoding', 'gzip, deflate');
  Header.Append('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');  
  Header.Append('Referer','http://steamcommunity.com/market/listings/570/Collar%20of%20Command/render/?query=&search_descriptions=0&start=0&count=10&country=RU&language=russian&currency=5');
  //Header.Append('Referer', 'http://steamcommunity.com/market/listings/570/Collar%20of%20Command');
  Header.Append('Origin', 'http://steamcommunity.com');
  Header.Append('Connection', 'keep-alive');
  Header.Append('Pragma', 'no-cache');
  Header.Append('Cache-Control', 'no-cache');
  Header.Append('Content-Length', Form1.Edit5.Text);
  Header.Append('Cookie','Steam_Language='+Steam_Language);
  Header.Append('Cookie','timezoneOffset='+timezoneOffset);
  Header.Append('Cookie','steamRememberLogin='+steamRememberLogin);
  Header.Append('Cookie','sessionid='+SessionID);
  Header.Append('Cookie','steamLogin='+steamLogin);
  Header.Append('Cookie','steamCC_46_52_135_42='+steamCC_46_52_135_42);
  Header.Append('Cookie','webTradeEligibility='+webTradeEligibility);
  Header.Append('Cookie','__utma='+__utma);
  Header.Append('Cookie','__utmz='+__utmz);
  Header.Append('Cookie','__utmb='+__utmb);
  Header.Append('Cookie','__utmc='+__utmc);
  
  Request.SetHeaderMap(Header);
 
  Data := TCefPostDataRef.New;
 
  Data.AddElement(CreateField('sessionid='+SessionID));
  Data.AddElement(CreateField('&currency=5'));
  Data.AddElement(CreateField('&subtotal='+inttostr(total-fee)));
  Data.AddElement(CreateField('&fee='+IntToStr(fee)));
  Data.AddElement(CreateField('&total='+IntToStr(total)));
 
  Request.PostData := Data;
 
  form1.Chromium1.Browser.MainFrame.LoadRequest(Request);
  
end;
//******************************************************************************