rename SkBitmapChecksummer as SkBitmapHasher, and prepare for it to possibly use

gm/gm_expectations.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef gm_expectations_DEFINED
 #define gm_expectations_DEFINED
 
 #include <stdarg.h>
 #include "gm.h"
 #include "SkBitmap.h"
-#include "SkBitmapChecksummer.h"
+#include "SkBitmapHasher.h"
 #include "SkData.h"
 #include "SkImageDecoder.h"
 #include "SkOSFile.h"
 #include "SkRefCnt.h"
 #include "SkStream.h"
 #include "SkTArray.h"
 
 #ifdef SK_BUILD_FOR_WIN
     // json includes xlocale which generates warning 4530 because we're compiling without
     // exceptions; see https://code.google.com/p/skia/issues/detail?id=1067
@@ skipping 63 matching lines @@
             fIgnoreFailure = ignoreFailure;
         }
 
         /**
          * Expect exactly one image (appropriate for the case when we
          * are comparing against a single PNG file).
          */
         Expectations(const SkBitmap& bitmap, bool ignoreFailure=kDefaultIgnoreFailure) {
             fBitmap = bitmap;
             fIgnoreFailure = ignoreFailure;
-            fAllowedChecksums.push_back() = SkBitmapChecksummer::Compute64(bitmap);
+            SkHashDigest digest;
+            // TODO(epoger): Better handling for error returned by ComputeDigest()?
+            // For now, we just report a digest of 0 in error cases, like before.
+            if (!SkBitmapHasher::ComputeDigest(bitmap, &digest)) {
+                digest = 0;
+            }
+            fAllowedChecksums.push_back() = digest;
         }
 
         /**
          * Create Expectations from a JSON element as found within the
          * kJsonKey_ExpectedResults section.
          *
          * It's fine if the jsonElement is null or empty; in that case, we just
          * don't have any expectations.
          */
         Expectations(Json::Value jsonElement) {
@@ skipping 249 matching lines @@
             }
             return true;
         }
 
         Json::Value fJsonRoot;
         Json::Value fJsonExpectedResults;
     };
 
 }
 #endif