Move backend-specific wxWebRequest headers to private subdirs

There is no need to make these headers public and keeping them private
will allow making backwards-incompatible changes to them in the future.

include/wx/osx/private/webrequest_urlsession.h

@@ -0,0 +1,112 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/osx/webrequest_urlsession.h
+// Purpose:     wxWebRequest implementation using URLSession
+// Author:      Tobias Taschner
+// Created:     2018-10-25
+// Copyright:   (c) 2018 wxWidgets development team
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_OSX_WEBREQUEST_URLSESSION_H
+#define _WX_OSX_WEBREQUEST_URLSESSION_H
+
+#if wxUSE_WEBREQUEST_URLSESSION
+
+DECLARE_WXCOCOA_OBJC_CLASS(NSURLSession);
+DECLARE_WXCOCOA_OBJC_CLASS(NSURLSessionTask);
+DECLARE_WXCOCOA_OBJC_CLASS(wxWebSessionDelegate);
+
+class wxWebSessionURLSession;
+class wxWebResponseURLSession;
+
+class WXDLLIMPEXP_NET wxWebResponseURLSession : public wxWebResponse
+{
+public:
+    wxWebResponseURLSession(wxWebRequest& request, WX_NSURLSessionTask task);
+
+    ~wxWebResponseURLSession();
+
+    wxInt64 GetContentLength() const wxOVERRIDE;
+
+    wxString GetURL() const wxOVERRIDE;
+
+    wxString GetHeader(const wxString& name) const wxOVERRIDE;
+
+    int GetStatus() const wxOVERRIDE;
+
+    wxString GetStatusText() const wxOVERRIDE;
+
+    wxString GetSuggestedFileName() const wxOVERRIDE;
+
+    void HandleData(WX_NSData data);
+
+private:
+    WX_NSURLSessionTask m_task;
+};
+
+class WXDLLIMPEXP_NET wxWebRequestURLSession : public wxWebRequest
+{
+public:
+    wxWebRequestURLSession(wxWebSessionURLSession& session, const wxString& url, int id);
+
+    ~wxWebRequestURLSession();
+
+    void Start() wxOVERRIDE;
+
+    void Cancel() wxOVERRIDE;
+
+    wxWebResponse* GetResponse() const wxOVERRIDE
+    { return m_response.get(); }
+
+    wxWebAuthChallenge* GetAuthChallenge() const wxOVERRIDE;
+
+    wxFileOffset GetBytesSent() const wxOVERRIDE;
+
+    wxFileOffset GetBytesExpectedToSend() const wxOVERRIDE;
+
+    wxFileOffset GetBytesReceived() const wxOVERRIDE;
+
+    wxFileOffset GetBytesExpectedToReceive() const wxOVERRIDE;
+
+    void HandleCompletion();
+
+private:
+    wxString m_url;
+    WX_NSURLSessionTask m_task;
+    wxScopedPtr<wxWebResponseURLSession> m_response;
+
+    wxDECLARE_NO_COPY_CLASS(wxWebRequestURLSession);
+};
+
+class WXDLLIMPEXP_NET wxWebSessionURLSession : public wxWebSession
+{
+public:
+    wxWebSessionURLSession();
+
+    ~wxWebSessionURLSession();
+
+    wxWebRequest* CreateRequest(const wxString& url, int id = wxID_ANY) wxOVERRIDE;
+
+    wxVersionInfo GetLibraryVersionInfo() wxOVERRIDE;
+
+    WX_NSURLSession GetSession() { return m_session; }
+
+    WX_wxWebSessionDelegate GetDelegate() { return m_delegate; }
+
+private:
+    WX_NSURLSession m_session;
+    WX_wxWebSessionDelegate m_delegate;
+
+    wxDECLARE_NO_COPY_CLASS(wxWebSessionURLSession);
+};
+
+class WXDLLIMPEXP_NET wxWebSessionFactoryURLSession : public wxWebSessionFactory
+{
+public:
+    wxWebSession* Create() wxOVERRIDE
+    { return new wxWebSessionURLSession(); }
+};
+
+#endif // wxUSE_WEBREQUEST_URLSESSION
+
+#endif // _WX_OSX_WEBREQUEST_URLSESSION_H