Don't copy image buffer when calculating size.

include/gpu/GrContext.h

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrContext_DEFINED
 #define GrContext_DEFINED
 
@@ skipping 468 matching lines @@
     static void TextBlobCacheOverBudgetCB(void* data);
 
     typedef SkRefCnt INHERITED;
 };
 
 /**
  * Can be used to perform actions related to the generating GrContext in a thread safe manner. The
  * proxy does not access the 3D API (e.g. OpenGL) that backs the generating GrContext.
  */
 class GrContextThreadSafeProxy : public SkRefCnt {
+public:
+    uint32_t uniqueID() const { return fContextUniqueID; }
+
 private:
     GrContextThreadSafeProxy(sk_sp<const GrCaps> caps, uint32_t uniqueID)
         : fCaps(std::move(caps))
         , fContextUniqueID(uniqueID) {}
 
     sk_sp<const GrCaps> fCaps;
     uint32_t            fContextUniqueID;
 
     friend class GrContext;
     friend class SkImage;
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif