Revert of Use presence of a content key as non-scratch indicator

src/gpu/GrResourceCache2.cpp

Index: src/gpu/GrResourceCache2.cpp
diff --git a/src/gpu/GrResourceCache2.cpp b/src/gpu/GrResourceCache2.cpp
index 76673cf9f95453cbed8a6fd3f81093d556ca2bff..85e66a7642ad45ea373eded4ef9c878fcb4ea181 100644
--- a/src/gpu/GrResourceCache2.cpp
+++ b/src/gpu/GrResourceCache2.cpp
@@ -67,15 +67,15 @@
             // either by drawing code or for pending io operations.
             // This will be removed when flush no longer creates resources.
             return resource->reffedOnlyByCache() && !resource->internalHasPendingIO() &&
-                   (NULL == resource->getContentKey());
+                   GrGpuResource::kYes_IsScratch == resource->fIsScratch;
         } else {
             // Because duties are currently shared between GrResourceCache and GrResourceCache2, the
             // current interpretation of this rule is that only GrResourceCache has a ref but that
             // it has been marked as a scratch resource.
-            return resource->reffedOnlyByCache() && (NULL == resource->getContentKey());
+            return resource->reffedOnlyByCache() &&
+                GrGpuResource::kYes_IsScratch == resource->fIsScratch;
         }
     }
-
 private:
     bool fFlushing;
 };