Make SkSHA1 and SkM5 use common SkDigestHash result type

src/utils/SkBitmapHasher.h

Index: src/utils/SkBitmapHasher.h
===================================================================
--- src/utils/SkBitmapHasher.h	(revision 8685)
+++ src/utils/SkBitmapHasher.h	(working copy)
@@ -12,9 +12,10 @@
 #include "SkBitmap.h"
 #include "SkBitmapTransformer.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): Soon, SkBitmapHasher will generate its results as an
+// SkHashDigest rather than SkUInt64HashDigest, and callers won't be
+// able to assume it converts to/from a uint64_t.
+typedef uint64_t SkUInt64HashDigest;
 
 /**
  * Static class that can generate an SkHashDigest from an SkBitmap.
@@ -31,12 +32,12 @@
      * 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, SkUInt64HashDigest *result);
 
 private:
     static bool ComputeDigestInternal(const SkBitmap& bitmap,
                                       const SkBitmapTransformer& transformer,
-                                      SkHashDigest *result);
+                                      SkUInt64HashDigest *result);
 };
 
 #endif