switch colorfilters to sk_sp

src/core/SkBlitter.cpp

Index: src/core/SkBlitter.cpp
diff --git a/src/core/SkBlitter.cpp b/src/core/SkBlitter.cpp
index 04897e3828af4ec077ec27102e88b279437969a8..2bf663c371db9fcee55b8ad9cd616cafe175107c 100644
--- a/src/core/SkBlitter.cpp
+++ b/src/core/SkBlitter.cpp
@@ -844,7 +844,8 @@ SkBlitter* SkBlitter::Choose(const SkPixmap& device,
     if (SkXfermode::IsMode(mode, SkXfermode::kClear_Mode)) {
         SkPaint* p = paint.writable();
         shader = p->setShader(nullptr);
-        cf = p->setColorFilter(nullptr);
+        p->setColorFilter(nullptr);
+        cf = nullptr;
         mode = p->setXfermodeMode(SkXfermode::kSrc_Mode);
         p->setColor(0);
     }