make InternalOnly_ functions actually private

Bug: skia:
Change-Id: Id06ad4283a0cd9835b3349c783b705b30435855a
Reviewed-on: https://skia-review.googlesource.com/87980
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index f8be87f..c8a4bc2 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -35,6 +35,7 @@
 #include "SkOSFile.h"
 #include "SkOSPath.h"
 #include "SkOpts.h"
+#include "SkPictureCommon.h"
 #include "SkPictureData.h"
 #include "SkPictureRecorder.h"
 #include "SkPipe.h"
@@ -1175,7 +1176,7 @@
         return SkRect::MakeEmpty();
     }
     SkPictInfo info;
-    if (!SkPicture::InternalOnly_StreamIsSKP(stream.get(), &info)) {
+    if (!SkPicture_StreamIsSKP(stream.get(), &info)) {
         return SkRect::MakeEmpty();
     }