GM: create GmResultDigest that encapsulates digest type ("bitmap-64bitMD5") and value (12345)

gm/gmmain.cpp

Index: gm/gmmain.cpp
===================================================================
--- gm/gmmain.cpp	(revision 9256)
+++ gm/gmmain.cpp	(working copy)
@@ -750,7 +750,7 @@
                                              const char *renderModeDescriptor,
                                              bool addToJsonSummary) {
         ErrorCombination errors;
-        SkHashDigest actualBitmapHash;
+        uint64_t actualBitmapHash;
         // 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(actualBitmap, &actualBitmapHash)) {
@@ -807,7 +807,7 @@
      * depending on errors encountered.
      */
     void add_actual_results_to_json_summary(const char testName[],
-                                            const SkHashDigest& actualResult,
+                                            uint64_t actualResult,
                                             ErrorCombination errors,
                                             bool ignoreFailure) {
         Json::Value jsonActualResults = ActualResultAsJsonValue(actualResult);
@@ -896,7 +896,7 @@
         } else {
             // If we are running without expectations, we still want to
             // record the actual results.
-            SkHashDigest actualBitmapHash;
+            uint64_t actualBitmapHash;
             // 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(actualBitmap, &actualBitmapHash)) {