SkPDF: allow overriding Producer metadata

include/core/SkDocument.h

Index: include/core/SkDocument.h
diff --git a/include/core/SkDocument.h b/include/core/SkDocument.h
index 9eed304a4030d45201de4b52b1ab02762c6550a1..042cf9aef26729ee7ca9d0253907d98c15676e9e 100644
--- a/include/core/SkDocument.h
+++ b/include/core/SkDocument.h
@@ -47,12 +47,23 @@ public:
      *  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.   */

[reed1, 2016/06/16 18:43:49]

How are the words delineated?

[hal.canary, 2016/06/30 14:13:03]

This is unspecified by the standard.

[hal.canary, 2016/06/30 14:44:20]

New verbage:

/*
 * 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,

[reed1, 2016/06/16 18:43:49]

nit:

1. our comments have the closing */ on its own line
2. properly our block comments should have a * at the beginning of each line
(not strictly enforced yet)

[hal.canary, 2016/06/30 14:13:03]

Done.

+            the name of the conforming product that created the
+            original document from which it was converted. */

[reed1, 2016/06/16 18:43:49]

If Creator means a tool/product, should we consider changing the name of the
field to more closely match that?

[hal.canary, 2016/06/30 14:13:03]

I would rather match what the standard says.

         SkString fCreator;
+        /** Leave fProducer empty to get the default, correct value. */

[reed1, 2016/06/16 18:43:49]

Lets first document what fProduce means, and then have a comment that says it
can be left blank to get the default.

[hal.canary, 2016/06/30 14:13:03]

Done.

+        SkString fProducer;
+        /** The date and time the document was created. */
         OptionalTimestamp fCreation;
+        /** The date and time the document was most recently modified. */
         OptionalTimestamp fModified;
     };