SkPixelSerializer is deprecated, so use simpler form of MakePDF

Bug: 
Change-Id: I33cde31a43e54240e4753177809445f7e28b3e9e
Reviewed-on: https://chromium-review.googlesource.com/826170Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Mike Reed <reed@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524172}

printing/common/pdf_metafile_utils.cc

@@ -39,8 +39,7 @@ sk_sp<SkDocument> MakePdfDocument(const std::string& creator,
   metadata.fCreator = creator.empty()
                           ? SkString("Chromium")
                           : SkString(creator.c_str(), creator.size());
-  return SkDocument::MakePDF(stream, SK_ScalarDefaultRasterDPI, metadata,
-                             nullptr, false);
+  return SkDocument::MakePDF(stream, metadata);
 }
 
 }  // namespace printing