Avoid separate allocation of SkImageCacherator

src/core/SkImageCacherator.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageCacherator_DEFINED
 #define SkImageCacherator_DEFINED
 
@@ skipping 50 matching lines @@
      */
     SkData* refEncoded(GrContext*);
 
     // Only return true if the generate has already been cached.
     bool lockAsBitmapOnlyIfAlreadyCached(SkBitmap*);
     // Call the underlying generator directly
     bool directGeneratePixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRB,
                               int srcX, int srcY);
 
 private:
-    SkImageCacherator(SkImageGenerator*, const SkImageInfo&, const SkIPoint&, uint32_t uniqueID);
+    struct Validator {
+        Validator(SkImageGenerator*, const SkIRect* subset);
+
+        operator bool() const { return fGenerator.get(); }
+
+        std::unique_ptr<SkImageGenerator> fGenerator;
+        SkImageInfo                       fInfo;
+        SkIPoint                          fOrigin;
+        uint32_t                          fUniqueID;
+    };
+
+    SkImageCacherator(Validator*);
 
     bool generateBitmap(SkBitmap*);
     bool tryLockAsBitmap(SkBitmap*, const SkImage*, SkImage::CachingHint);
 #if SK_SUPPORT_GPU
     // Returns the texture. If the cacherator is generating the texture and wants to cache it,
     // it should use the passed in key (if the key is valid).
     GrTexture* lockTexture(GrContext*, const GrUniqueKey& key, const SkImage* client,
                            SkImage::CachingHint, bool willBeMipped, SkSourceGammaTreatment);
 #endif
 
@@ skipping 11 matching lines @@
     };
 
     SkMutex                         fMutexForGenerator;
     SkAutoTDelete<SkImageGenerator> fNotThreadSafeGenerator;
 
     const SkImageInfo   fInfo;
     const SkIPoint      fOrigin;
     const uint32_t      fUniqueID;
 
     friend class GrImageTextureMaker;
+    friend class SkImage;
+    friend class SkImage_Generator;
 };
 
 #endif