Make textures register with GrResourceCache2 as scratch.

include/gpu/GrGpuResource.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGpuResource_DEFINED
 #define GrGpuResource_DEFINED
 
 #include "SkInstCnt.h"
 #include "SkTInternalLList.h"
+#include "GrResourceKey.h"
 
 class GrResourceCacheEntry;
 class GrResourceCache2;
 class GrGpu;
 class GrContext;
 
 /**
  * Base class for objects that can be kept in the GrResourceCache.
  */
 class GrGpuResource : public SkNoncopyable {
@@ skipping 52 matching lines @@
      * approximate since we aren't aware of additional padding or copies made
      * by the driver.
      *
      * @return the amount of GPU memory used in bytes
      */
     virtual size_t gpuMemorySize() const = 0;
 
     void setCacheEntry(GrResourceCacheEntry* cacheEntry) { fCacheEntry = cacheEntry; }
     GrResourceCacheEntry* getCacheEntry() { return fCacheEntry; }
 
+    /** 
+     * If this resource can be used as a scratch resource this returns a valid
+     * scratch key. Otherwise it returns a key for which isNullScratch is true.
+     */
+    const GrResourceKey& getScratchKey() const { return fScratchKey; }
+
     /**
      * Gets an id that is unique for this GrCacheable object. It is static in that it does
      * not change when the content of the GrCacheable object changes. This will never return
      * 0.
      */
     uint32_t getUniqueID() const { return fUniqueID; }
 
 protected:
-
     // This must be called by every GrGpuObject. It should be called once the object is fully
     // initialized (i.e. not in a base class constructor).
     void registerWithCache();
 
     GrGpuResource(GrGpu*, bool isWrapped);
     virtual ~GrGpuResource();
 
     bool isInCache() const { return NULL != fCacheEntry; }
 
     GrGpu* getGpu() const { return fGpu; }
 
     // Derived classes should always call their parent class' onRelease
     // and onAbandon methods in their overrides.
     virtual void onRelease() {};
     virtual void onAbandon() {};
 
     bool isWrapped() const { return kWrapped_FlagBit & fFlags; }
 
     /**
      * This entry point should be called whenever gpuMemorySize() begins
      * reporting a different size. If the object is in the cache, it will call
      * gpuMemorySize() immediately and pass the new size on to the resource
      * cache.
      */
     void didChangeGpuMemorySize() const;
 
+    /**
+     * Optionally called by the GrGpuResource subclass if the resource can be used as scratch.
+     * By default resources are not usable as scratch. This should only be called once.
+     **/
+    void setScratchKey(const GrResourceKey& scratchKey);
+
 private:
 #ifdef SK_DEBUG
     friend class GrGpu; // for assert in GrGpu to access getGpu
 #endif
 
     static uint32_t CreateUniqueID();
 
     // We're in an internal doubly linked list owned by GrResourceCache2
     SK_DECLARE_INTERNAL_LLIST_INTERFACE(GrGpuResource);
 
     // This is not ref'ed but abandon() or release() will be called before the GrGpu object
     // is destroyed. Those calls set will this to NULL.
     GrGpu* fGpu;
 
     enum Flags {
         /**
          * This object wraps a GPU object given to us by the user.
          * Lifetime management is left up to the user (i.e., we will not
          * free it).
          */
         kWrapped_FlagBit         = 0x1,
     };
 
     uint32_t                fFlags;
 
     mutable int32_t         fRefCnt;
     GrResourceCacheEntry*   fCacheEntry;  // NULL if not in cache
     const uint32_t          fUniqueID;
 
+    GrResourceKey           fScratchKey;
+
     typedef SkNoncopyable INHERITED;
 };
 
 #endif