Delete copyTo(Allocator), hide copyTo() behind flag

Replace uses of copyTo() in Skia.

Bug: skia:6464
Change-Id: I921dc53a1c29a5176d18f05741f7c0b5a008e548
Reviewed-on: https://skia-review.googlesource.com/14502
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/tools/skdiff/skdiff_utils.cpp b/tools/skdiff/skdiff_utils.cpp
index 05e1c50..7a1b7e8 100644
--- a/tools/skdiff/skdiff_utils.cpp
+++ b/tools/skdiff/skdiff_utils.cpp
@@ -80,7 +80,7 @@
 
 bool write_bitmap(const SkString& path, const SkBitmap& bitmap) {
     SkBitmap copy;
-    bitmap.copyTo(&copy, kN32_SkColorType);
+    sk_tool_utils::copy_to(&copy, kN32_SkColorType, bitmap);
     force_all_opaque(copy);
     return sk_tool_utils::EncodeImageToFile(path.c_str(), copy,
                                       SkEncodedImageFormat::kPNG, 100);