GM: add --writeChecksumBasedFilenames option

gm/gm_expectations.cpp

Index: gm/gm_expectations.cpp
===================================================================
--- gm/gm_expectations.cpp	(revision 9681)
+++ gm/gm_expectations.cpp	(working copy)
@@ -109,7 +109,24 @@
         return jsonTypeValuePair;
     }
 
+    SkString GmResultDigest::getHashType() const {
+        // TODO(epoger): The current implementation assumes that the
+        // result digest is always of type kJsonKey_Hashtype_Bitmap_64bitMD5
+        return SkString(kJsonKey_Hashtype_Bitmap_64bitMD5);
+    }
 
+    SkString GmResultDigest::getDigestValue() const {
+        // TODO(epoger): The current implementation assumes that the
+        // result digest is always of type kJsonKey_Hashtype_Bitmap_64bitMD5
+        //
+        // TODO(epoger): If SkString had an appendU64() method, it would be
+        // more efficient to use that here... but it doesn't.
+        SkString retval;
+        retval.printf("%lu", fHashDigest);
+        return retval;
+    }
+
+
     // Expectations class...
 
     Expectations::Expectations(bool ignoreFailure) {