Use presence of a content key as non-scratch indicator

include/gpu/GrGpuResource.h

Index: include/gpu/GrGpuResource.h
diff --git a/include/gpu/GrGpuResource.h b/include/gpu/GrGpuResource.h
index 947019b95a9af4e5587535deea11ae8548cfd1a8..8596d40134671ae59b8c29d1244883395c841be8 100644
--- a/include/gpu/GrGpuResource.h
+++ b/include/gpu/GrGpuResource.h
@@ -69,7 +69,7 @@ public:
     }
 
 protected:
-    GrIORef() : fRefCnt(1), fPendingReads(0), fPendingWrites(0), fIsScratch(kNo_IsScratch) { }
+    GrIORef() : fRefCnt(1), fPendingReads(0), fPendingWrites(0) { }
 
     bool internalHasPendingRead() const { return SkToBool(fPendingReads); }
     bool internalHasPendingWrite() const { return SkToBool(fPendingWrites); }
@@ -116,16 +116,7 @@ private:
 
     // This class is used to manage conversion of refs to pending reads/writes.
     friend class GrGpuResourceRef;
-
-    // This is temporary until GrResourceCache is fully replaced by GrResourceCache2.
-    enum IsScratch {
-        kNo_IsScratch,
-        kYes_IsScratch
-    } fIsScratch;
-
-    friend class GrContext; // to set the above field.
-    friend class GrResourceCache; // to check the above field.
-    friend class GrResourceCache2; // to check the above field.
+    friend class GrResourceCache2; // to check IO ref counts.
 
     template <typename, GrIOType> friend class GrPendingIOResource;
 };
@@ -188,6 +179,12 @@ public:
      */
     const GrResourceKey& getScratchKey() const { return fScratchKey; }
 
+    /** 
+     * If this resource is currently cached by its contents then this will return
+     * the content key. Otherwise, NULL is returned.
+     */
+    const GrResourceKey* getContentKey() const;
+
     /**
      * Gets an id that is unique for this GrGpuResource object. It is static in that it does
      * not change when the content of the GrGpuResource object changes. This will never return