SkPDF: fix PDFA-only metadata error

src/pdf/SkPDFMetadata.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMD5.h"
 #include "SkMilestone.h"
 #include "SkPDFMetadata.h"
@@ skipping 296 matching lines @@
             metadata.fSubject,
             "<dc:description><rdf:Alt><rdf:li xml:lang=\"x-default\">",
             "</rdf:li></rdf:Alt></dc:description>\n");
     SkString keywords1 =
             escape_xml(metadata.fKeywords, "<dc:subject><rdf:Bag><rdf:li>",
                        "</rdf:li></rdf:Bag></dc:subject>\n");
     SkString keywords2 = escape_xml(metadata.fKeywords, "<pdf:Keywords>",
                                     "</pdf:Keywords>\n");
     // TODO: in theory, keywords can be a list too.
 
-    SkString producer("<pdf:Producer>SKPDF_PRODUCER</pdf:Producer>\n");
+    SkString producer("<pdf:Producer>" SKPDF_PRODUCER "</pdf:Producer>\n");
     if (!metadata.fProducer.isEmpty()) {
         // TODO: register a developer prefix to make
         // <skia:SKPDF_CUSTOM_PRODUCER_KEY> a real XML tag.
         producer = escape_xml(
                 metadata.fProducer, "<pdf:Producer>",
                 "</pdf:Producer>\n<!-- <skia:" SKPDF_CUSTOM_PRODUCER_KEY ">"
                 SKPDF_PRODUCER "</skia:" SKPDF_CUSTOM_PRODUCER_KEY "> -->\n");
     }
 
     SkString creator = escape_xml(metadata.fCreator, "<xmp:CreatorTool>",
                                   "</xmp:CreatorTool>\n");
     SkString documentID = uuid_to_string(doc);  // no need to escape
     SkASSERT(0 == count_xml_escape_size(documentID));
     SkString instanceID = uuid_to_string(instance);
     SkASSERT(0 == count_xml_escape_size(instanceID));
     return sk_make_sp<PDFXMLObject>(SkStringPrintf(
             templateString, modificationDate.c_str(), creationDate.c_str(),
             creator.c_str(), title.c_str(), subject.c_str(), author.c_str(),
             keywords1.c_str(), documentID.c_str(), instanceID.c_str(),
             producer.c_str(), keywords2.c_str()));
 }
 
 #undef SKPDF_CUSTOM_PRODUCER_KEY
 #undef SKPDF_PRODUCER
 #undef SKPDF_STRING
 #undef SKPDF_STRING_IMPL