Revert 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 bbe70a7e4a5bab1fc364e0d7c6dfb95d862619f3..d0cb8d58409375a571af662d399c83875d7a6b08 100644
--- a/src/image/SkImage_Base.h
+++ b/src/image/SkImage_Base.h
@@ -56,6 +56,10 @@
     // 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; }
+
     // newWidth > 0, newHeight > 0, subset either nullptr or a proper subset of this bounds
     virtual SkImage* onNewImage(int newWidth, int newHeight, const SkIRect* subset,
                                 SkFilterQuality) const;