Removed NativeMetafile and PreviewMetafile typedef as it's always PdfMetafileSkia.

content/renderer/pepper/pepper_plugin_instance_impl.cc

Index: content/renderer/pepper/pepper_plugin_instance_impl.cc
diff --git a/content/renderer/pepper/pepper_plugin_instance_impl.cc b/content/renderer/pepper/pepper_plugin_instance_impl.cc
index b9170f4cfb29cc8997efb2bc932321ac8d741c2f..ded5327fdaf4281c12b7d8b5d61c623aa453f631 100644
--- a/content/renderer/pepper/pepper_plugin_instance_impl.cc
+++ b/content/renderer/pepper/pepper_plugin_instance_impl.cc
@@ -133,7 +133,7 @@
 #endif
 
 #if defined(OS_MACOSX)
-#include "printing/metafile_impl.h"
+#include "printing/pdf_metafile_skia.h"
 #endif  // defined(OS_MACOSX)
 
 #if defined(OS_WIN)
@@ -1951,9 +1951,6 @@ bool PepperPluginInstanceImpl::PrintPDFOutput(PP_Resource print_output,
 
   bool ret = false;
 #if defined(OS_POSIX) && !defined(OS_ANDROID)
-  // On Linux we just set the final bits in the native metafile
-  // (NativeMetafile and PreviewMetafile must have compatible formats,
-  // i.e. both PDF for this to work).
   printing::Metafile* metafile =
       printing::MetafileSkiaWrapper::GetMetafileFromCanvas(*canvas);
   DCHECK(metafile != NULL);