change old picture serialization to really handle images

BUG=skia:3965

Review URL: https://codereview.chromium.org/1199473002
diff --git a/tests/CachedDecodingPixelRefTest.cpp b/tests/CachedDecodingPixelRefTest.cpp
index 66e5273..465b69b 100644
--- a/tests/CachedDecodingPixelRefTest.cpp
+++ b/tests/CachedDecodingPixelRefTest.cpp
@@ -249,7 +249,7 @@
         // Ignore factory; use global cache.
         success = SkCachingPixelRef::Install(gen.detach(), &lazy);
     } else {
-        success = SkInstallDiscardablePixelRef(gen.detach(), &lazy, factory);
+        success = SkInstallDiscardablePixelRef(gen.detach(), NULL, &lazy, factory);
     }
     REPORTER_ASSERT(reporter, success);
     if (TestImageGenerator::kSucceedGetPixels_TestType == type) {