Revert of Revert[2] of add ImageShader, sharing code with its Bitmap cousin

src/image/SkImage_Base.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImage_Base_DEFINED
 #define SkImage_Base_DEFINED
 
@@ skipping 36 matching lines @@
 
     virtual GrTexture* peekTexture() const { return nullptr; }
 
     // return a read-only copy of the pixels. We promise to not modify them,
     // but only inspect them (or encode them).
     virtual bool getROPixels(SkBitmap*) const = 0;
 
     // Caller must call unref when they are done.
     virtual GrTexture* asTextureRef(GrContext*, SkImageUsageType) const = 0;
 
+    virtual SkShader* onNewShader(SkShader::TileMode,
+                                  SkShader::TileMode,
+                                  const SkMatrix* localMatrix) const { return nullptr; }
+
     virtual SkImage* onNewSubset(const SkIRect&) const = 0;
-
     virtual SkData* onRefEncoded() const { return nullptr; }
 
     virtual bool onAsLegacyBitmap(SkBitmap*, LegacyBitmapMode) const;
 
     virtual bool onIsLazyGenerated() const { return false; }
 
     // Call when this image is part of the key to a resourcecache entry. This allows the cache
     // to know automatically those entries can be purged when this SkImage deleted.
     void notifyAddedToCache() const {
         fAddedToCache.store(true);
@@ skipping 10 matching lines @@
 
 static inline SkImage_Base* as_IB(SkImage* image) {
     return static_cast<SkImage_Base*>(image);
 }
 
 static inline const SkImage_Base* as_IB(const SkImage* image) {
     return static_cast<const SkImage_Base*>(image);
 }
 
 #endif