Offer single-param version of deepCopyTo -- much easier to migrate to colortypes

src/pdf/SkPDFImage.cpp

Index: src/pdf/SkPDFImage.cpp
diff --git a/src/pdf/SkPDFImage.cpp b/src/pdf/SkPDFImage.cpp
index 81adcc20d6b4c671229619c686794652d3d801cc..f39dc5908502bef96dd70b40cbba248cd82ece61 100644
--- a/src/pdf/SkPDFImage.cpp
+++ b/src/pdf/SkPDFImage.cpp
@@ -507,7 +507,7 @@ SkPDFImage::SkPDFImage(SkStream* stream,
     if (bitmap.isImmutable()) {
         fBitmap = bitmap;
     } else {
-        bitmap.deepCopyTo(&fBitmap, bitmap.config());
+        bitmap.deepCopyTo(&fBitmap);
         fBitmap.setImmutable();
     }