Revert[4] of add ImageShader, sharing code with its Bitmap cousin

src/image/SkImage_Base.h

Index: src/image/SkImage_Base.h
diff --git a/src/image/SkImage_Base.h b/src/image/SkImage_Base.h
index bbcf182ab8d5c9aca6baa76e65b7ded92ea885ac..757262ad3dc30e0b6643e0b99de612461bf079e5 100644
--- a/src/image/SkImage_Base.h
+++ b/src/image/SkImage_Base.h
@@ -54,11 +54,8 @@ public:
     // 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;