change SkStreams to work with sk_sp<SkData> instead of SkData*

tests/PDFDocumentTest.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "Test.h"
 
 #include "Resources.h"
 #include "SkCanvas.h"
@@ skipping 175 matching lines @@
     SkDocument::PDFMetadata pdfMetadata;
     pdfMetadata.fTitle = "test document";
     pdfMetadata.fCreation.fEnabled = true;
     pdfMetadata.fCreation.fDateTime = {0, 1999, 12, 5, 31, 23, 59, 59};
 
     SkDynamicMemoryWStream buffer;
     auto doc = SkDocument::MakePDF(&buffer, SK_ScalarDefaultRasterDPI,
                                    pdfMetadata, nullptr, /* pdfa = */ true);
     doc->beginPage(64, 64)->drawColor(SK_ColorRED);
     doc->close();
-    sk_sp<SkData> data(buffer.copyToData());
-    buffer.reset();
+    sk_sp<SkData> data(buffer.detachAsData());
+
     static const char* expectations[] = {
         "sRGB IEC61966-2.1",
         "<dc:title><rdf:Alt><rdf:li xml:lang=\"x-default\">test document",
         "<xmp:CreateDate>1999-12-31T23:59:59+00:00</xmp:CreateDate>",
         "/Subtype /XML",
         "/CreationDate (D:19991231235959+00'00')>>",
     };
     for (const char* expectation : expectations) {
         if (!contains(data->bytes(), data->size(), expectation)) {
             ERRORF(r, "PDFA expectation missing: '%s'.", expectation);
         }
     }
     pdfMetadata.fProducer = "phoney library";
     doc = SkDocument::MakePDF(&buffer, SK_ScalarDefaultRasterDPI,
                               pdfMetadata, nullptr, /* pdfa = */ true);
     doc->beginPage(64, 64)->drawColor(SK_ColorRED);
     doc->close();
-    data.reset(buffer.copyToData());
-    buffer.reset();
+    data = buffer.detachAsData();
 
     static const char* moreExpectations[] = {
         "/Producer (phoney library)",
         "/ProductionLibrary (Skia/PDF m",
         "<!-- <skia:ProductionLibrary>Skia/PDF m",
         "<pdf:Producer>phoney library</pdf:Producer>",
     };
     for (const char* expectation : moreExpectations) {
         if (!contains(data->bytes(), data->size(), expectation)) {
             ERRORF(r, "PDFA expectation missing: '%s'.", expectation);
         }
     }
 }