add new copyTo version to SkBitmap, which takes SkColorType

src/utils/SkBitmapHasher.cpp

Index: src/utils/SkBitmapHasher.cpp
diff --git a/src/utils/SkBitmapHasher.cpp b/src/utils/SkBitmapHasher.cpp
index 9f0affdea7dbd733194870597374e5a0ccdcc938..6c861cd04bc261c52e35c1d1769703c295b8e611 100644
--- a/src/utils/SkBitmapHasher.cpp
+++ b/src/utils/SkBitmapHasher.cpp
@@ -57,7 +57,7 @@ static inline uint64_t first_8_bytes_as_uint64(const uint8_t *bytearray) {
     // Hmm, that didn't work. Maybe if we create a new
     // kARGB_8888_Config version of the bitmap it will work better?
     SkBitmap copyBitmap;
-    if (!bitmap.copyTo(&copyBitmap, SkBitmap::kARGB_8888_Config)) {
+    if (!bitmap.copyTo(&copyBitmap, kPMColor_SkColorType)) {
         return false;
     }
     return ComputeDigestInternal(copyBitmap, result);