Hide SkTextBlob::GlyphPositioning from public API

Make private, add corresponding SkTextBlobRunIterator enum.

Also move SkTextBlobRunIterator to SkTextBlobPriv.h.

Change-Id: If3e0beabb0e8484b1ac73c6fc0827e920ca1f93b
Reviewed-on: https://skia-review.googlesource.com/142501
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Reviewed-by: Cary Clark <caryclark@google.com>
diff --git a/src/pdf/SkPDFDevice.h b/src/pdf/SkPDFDevice.h
index 2075202..7bd1a0e 100644
--- a/src/pdf/SkPDFDevice.h
+++ b/src/pdf/SkPDFDevice.h
@@ -19,7 +19,7 @@
 #include "SkSinglyLinkedList.h"
 #include "SkStream.h"
 #include "SkTDArray.h"
-#include "SkTextBlob.h"
+#include "SkTextBlobPriv.h"
 #include "SkKeyedImage.h"
 
 class SkGlyphRunList;
@@ -241,7 +241,6 @@
 
     int getFontResourceIndex(SkTypeface* typeface, uint16_t glyphID);
 
-
     void internalDrawGlyphRun(const SkGlyphRun& glyphRun, SkPoint offset);
 
     void internalDrawPaint(const SkPaint& paint, ContentEntry* contentEntry);