Create a Factory for NativeMetafile.

printing/native_metafile_factory.h

Index: printing/native_metafile_factory.h
diff --git a/printing/native_metafile_factory.h b/printing/native_metafile_factory.h
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+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PRINTING_NATIVE_METAFILE_FACTORY_H_
+#define PRINTING_NATIVE_METAFILE_FACTORY_H_
+
+#include "base/basictypes.h"
+#include "printing/native_metafile.h"
+
+#if defined(OS_WIN)
+#include "printing/emf_win.h"
+#elif defined(OS_MACOSX)
+#include "printing/pdf_metafile_mac.h"
+#elif defined(OS_POSIX)
+#include "printing/pdf_ps_metafile_cairo.h"
+#endif
+
+namespace printing {
+
+// Various printing contexts will be supported in the future (cairo, skia, emf).
+// So this class returns the appropriate context depending on the platform and
+// user preferences.
+// (Note: For the moment there is only one option per platform.)
+class NativeMetafileFactory {
+ public:
+
+  // This method takes care of returning a pointer to the appropriate
+  // NativeMetafile object according to the platform.
+  static printing::NativeMetafile* CreateMetafile();
+
+ private:
+  NativeMetafileFactory();
+  DISALLOW_COPY_AND_ASSIGN(NativeMetafileFactory);
+};
+
+}  // namespace printing
+
+#endif  // PRINTING_NATIVE_METAFILE_FACTORY_H_