Can't hurt to make this SkNoncopyable.

BUG=skia:
R=bungeman@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/510953002
diff --git a/src/core/SkRecords.h b/src/core/SkRecords.h
index f216897..bd65fc5 100644
--- a/src/core/SkRecords.h
+++ b/src/core/SkRecords.h
@@ -180,7 +180,7 @@
 
 // Like SkBitmap, but deep copies pixels if they're not immutable.
 // Using this, we guarantee the immutability of all bitmaps we record.
-class ImmutableBitmap {
+class ImmutableBitmap : SkNoncopyable {
 public:
     explicit ImmutableBitmap(const SkBitmap& bitmap) {
         if (bitmap.isImmutable()) {