Switch SkSpecialImage & SkSpecialSurface classes over to smart pointers

gm/offsetimagefilter.cpp

Index: gm/offsetimagefilter.cpp
diff --git a/gm/offsetimagefilter.cpp b/gm/offsetimagefilter.cpp
index 15cf0450d89b4477e084e5ee0c0ec140c434d495..dd33d9db7ca04a47388b0078d36d701d4a870887 100644
--- a/gm/offsetimagefilter.cpp
+++ b/gm/offsetimagefilter.cpp
@@ -47,7 +47,7 @@ protected:
         SkPaint paint;
 
         for (int i = 0; i < 4; i++) {
-            const SkImage* image = (i & 0x01) ? fCheckerboard.get() : fBitmap.get();
+            SkImage* image = (i & 0x01) ? fCheckerboard.get() : fBitmap.get();
             SkIRect cropRect = SkIRect::MakeXYWH(i * 12,
                                                  i * 8,
                                                  image->width() - i * 8,