Cleanup of code that converts from GPU-backed resources to SkImageInfo

src/image/SkImage_Gpu.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 SkImage_Gpu_DEFINED
 #define SkImage_Gpu_DEFINED
 
 #include "SkAtomics.h"
 #include "GrTexture.h"
 #include "GrGpuResourcePriv.h"
 #include "SkBitmap.h"
 #include "SkGr.h"
 #include "SkImage_Base.h"
 #include "SkImagePriv.h"
 #include "SkSurface.h"
 
 class SkImage_Gpu : public SkImage_Base {
 public:
     /**
      *  An "image" can be a subset/window into a larger texture, so we explicit take the
      *  width and height.
      */
     SkImage_Gpu(int w, int h, uint32_t uniqueID, SkAlphaType, GrTexture*, sk_sp<SkColorSpace>,
                 SkBudgeted);
     ~SkImage_Gpu() override;
 
-    SkImageInfo onImageInfo() const override {
-        return GrMakeInfoFromTexture(fTexture, fTexture->width(), fTexture->height(), isOpaque(),
-                                     fColorSpace);
-    }
+    SkImageInfo onImageInfo() const override;
 
     void applyBudgetDecision() const {
         if (SkBudgeted::kYes == fBudgeted) {
             fTexture->resourcePriv().makeBudgeted();
         } else {
             fTexture->resourcePriv().makeUnbudgeted();
         }
     }
 
     bool getROPixels(SkBitmap*, CachingHint) const override;
@@ skipping 15 matching lines @@
     const SkAlphaType           fAlphaType;
     const SkBudgeted            fBudgeted;
     sk_sp<SkColorSpace>         fColorSpace;
     mutable SkAtomic<bool>      fAddedRasterVersionToCache;
 
 
     typedef SkImage_Base INHERITED;
 };
 
 #endif