Make SkSHA1 and SkM5 use common SkDigestHash result type

src/utils/SkBitmapHasher.h

Index: src/utils/SkBitmapHasher.h
===================================================================
--- src/utils/SkBitmapHasher.h	(revision 8826)
+++ src/utils/SkBitmapHasher.h	(working copy)
@@ -11,11 +11,21 @@
 
 #include "SkBitmap.h"
 #include "SkBitmapTransformer.h"
+#include "SkHashDigest.h"
 
-// TODO(epoger): Soon, SkHashDigest will become a real class of its own,
-// and callers won't be able to assume it converts to/from a uint64_t.
-typedef uint64_t SkHashDigest;
+// TODO(epoger): Once we figure out which bitmap hash algorithm to use
+// long-term, pick one BITMAP_HASH_TYPE setting and delete the unused code.
+//
+// For now, disable this to keep the old uint64_t bitmap hash.
+#define BITMAP_HASH_TYPE_SkHashDigest
 
+// Set automatically using the above.
+#ifdef BITMAP_HASH_TYPE_SkHashDigest
+  #define BITMAP_HASH_TYPE SkHashDigest
+#else
+  #define BITMAP_HASH_TYPE uint64_t
+#endif
+
 /**
  * Static class that can generate an SkHashDigest from an SkBitmap.
  */
@@ -31,12 +41,12 @@
      * intermediate SkBitmap and copy the pixels over to it... so in some
      * cases, performance and memory usage can suffer.
      */
-    static bool ComputeDigest(const SkBitmap& bitmap, SkHashDigest *result);
+    static bool ComputeDigest(const SkBitmap& bitmap, BITMAP_HASH_TYPE *result);
 
 private:
     static bool ComputeDigestInternal(const SkBitmap& bitmap,
                                       const SkBitmapTransformer& transformer,
-                                      SkHashDigest *result);
+                                      BITMAP_HASH_TYPE *result);
 };
 
 #endif