SkPDF: allow overriding Producer metadata

include/core/SkDocument.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkDocument_DEFINED
 #define SkDocument_DEFINED
 
@@ skipping 29 matching lines @@
     struct OptionalTimestamp {
         SkTime::DateTime fDateTime;
         bool fEnabled;
         OptionalTimestamp() : fEnabled(false) {}
     };
 
     /**
      *  Optional metadata to be passed into the PDF factory function.
      */
     struct PDFMetadata {
+        /**
+         * The document’s title.
+         */
         SkString fTitle;
+        /**
+         * The name of the person who created the document.
+         */
         SkString fAuthor;
+        /**
+         * The subject of the document.
+         */
         SkString fSubject;
+        /**
+         * Keywords associated with the document.  Commas may be used
+         * to delineate keywords within the string.
+         */
         SkString fKeywords;
+        /**
+         * If the document was converted to PDF from another format,
+         * the name of the conforming product that created the
+         * original document from which it was converted.
+         */
         SkString fCreator;
+        /**
+         * The product that is converting this document to PDF.
+         *
+         * Leave fProducer empty to get the default, correct value.
+         */
+        SkString fProducer;
+        /**
+         * The date and time the document was created.
+         */
         OptionalTimestamp fCreation;
+        /**
+         * The date and time the document was most recently modified.
+         */
         OptionalTimestamp fModified;
     };
 
     /**
      *  Create a PDF-backed document, writing the results into a
      *  SkWStream.
      *
      *  PDF pages are sized in point units. 1 pt == 1/72 inch ==
      *  127/360 mm.
      *
@@ skipping 205 matching lines @@
 
 private:
     SkWStream* fStream;
     void       (*fDoneProc)(SkWStream*, bool aborted);
     State      fState;
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif