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

src/core/SkBitmapHeap.cpp

Index: src/core/SkBitmapHeap.cpp
diff --git a/src/core/SkBitmapHeap.cpp b/src/core/SkBitmapHeap.cpp
index da628937e90389f34686b866f59ec8197cdd4d0d..efaa23fc64acd5ec6687fc7283cb70aca3c8253a 100644
--- a/src/core/SkBitmapHeap.cpp
+++ b/src/core/SkBitmapHeap.cpp
@@ -265,7 +265,7 @@ bool SkBitmapHeap::copyBitmap(const SkBitmap& originalBitmap, SkBitmap& copiedBi
 //        copiedBitmap.setPixelRef(sharedPixelRef, originalBitmap.pixelRefOffset());
     } else if (originalBitmap.empty()) {
         copiedBitmap.reset();
-    } else if (!originalBitmap.deepCopyTo(&copiedBitmap, originalBitmap.config())) {
+    } else if (!originalBitmap.deepCopyTo(&copiedBitmap)) {
         return false;
     }
     copiedBitmap.setImmutable();