forgot base impl

BUG=skia:
TBR=fmalita

Review URL: https://codereview.chromium.org/1323173002

src/image/SkImage.cpp

diff --git a/src/image/SkImage.cpp b/src/image/SkImage.cpp
index 05b6d45..c55d28a 100644
--- a/src/image/SkImage.cpp
+++ b/src/image/SkImage.cpp
@@ -53,6 +53,10 @@
     return as_IB(this)->onReadPixels(rec.fInfo, rec.fPixels, rec.fRowBytes, rec.fX, rec.fY);
 }
 
+void SkImage::preroll(GrContext* ctx) const {
+    as_IB(this)->onPreroll(ctx);
+}
+
 SkShader* SkImage::newShader(SkShader::TileMode tileX,
                              SkShader::TileMode tileY,
                              const SkMatrix* localMatrix) const {