SkPDF: More IndirectRefs

  * Reserve PDFIndirectReference for each new page.
  * SkPDFDocument::getPage returns PDFIndirectReference.
  * SkPDFDevice::appendDests takes a PDFIndirectReference.
  * generate_page_tree() respects page reservations, and
    returns PDFIndirectReference.
  * SkPDFDocument::fDests no longer sk_sp<>.
  * ProcSets moved back to ResourceDict.
  * StructTreeRoot builder moved to SkPDFTag::MakeStructTree.

Bug: skia:8630

Change-Id: Ie22e6b47d6d7b40bc47434794d26f7c43b7b241c
Reviewed-on: https://skia-review.googlesource.com/c/178934
Auto-Submit: Hal Canary <halcanary@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
diff --git a/src/pdf/SkPDFDevice.h b/src/pdf/SkPDFDevice.h
index c709d59..46fc64b 100644
--- a/src/pdf/SkPDFDevice.h
+++ b/src/pdf/SkPDFDevice.h
@@ -108,7 +108,7 @@
      *  @param dict  Dictionary to add destinations to.
      *  @param page  The PDF object representing the page for this device.
      */
-    void appendDestinations(SkPDFDict* dict, SkPDFObject* page) const;
+    void appendDestinations(SkPDFDict* dict, SkPDFIndirectReference page) const;
 
     /** Returns a SkStream with the page contents.
      */