simplify GrTextureAdjuster given there is only one subclass

src/gpu/GrImageIDTextureAdjuster.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 GrImageIDTextureAdjuster_DEFINED
 #define GrImageIDTextureAdjuster_DEFINED
 
 #include "GrTextureParamsAdjuster.h"
 #include "SkImage.h"
 
 class SkBitmap;
 class SkImage_Base;
 class SkImageCacherator;
 
-/** Implementation for texture-backed SkImages. The image must stay in scope and unmodified while
-    this object exists. */
 class GrImageTextureAdjuster : public GrTextureAdjuster {
 public:
     explicit GrImageTextureAdjuster(const SkImage_Base* img);
-
-protected:
-    SkColorSpace* getColorSpace() override;
-
-private:
-    void makeCopyKey(const CopyParams& params, GrUniqueKey* copyKey) override;
-
-    void didCacheCopy(const GrUniqueKey& copyKey) override;
-
-    const SkImage_Base* fImageBase;
-
-    typedef GrTextureAdjuster INHERITED;
 };
 
 /** This class manages the conversion of SW-backed bitmaps to GrTextures. If the input bitmap is
     non-volatile the texture is cached using a key created from the pixels' image id and the
     subset of the pixelref specified by the bitmap. */
 class GrBitmapTextureMaker : public GrTextureMaker {
 public:
     GrBitmapTextureMaker(GrContext* context, const SkBitmap& bitmap);
 
 protected:
@@ skipping 33 matching lines @@
 private:
     SkImageCacherator*      fCacher;
     const SkImage*          fClient;
     GrUniqueKey             fOriginalKey;
     SkImage::CachingHint    fCachingHint;
 
     typedef GrTextureMaker INHERITED;
 };
 
 #endif