guard rasterizer and drawlooper setters

Need to land https://codereview.chromium.org/1823513002/ first

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1821533002

Review URL: https://codereview.chromium.org/1821533002
diff --git a/gm/shadows.cpp b/gm/shadows.cpp
index 5696240..6263af2 100644
--- a/gm/shadows.cpp
+++ b/gm/shadows.cpp
@@ -54,45 +54,36 @@
     }
 
     void onDraw(SkCanvas* canvas) override {
-        SkDrawLooper* shadowLoopers[5];
-        shadowLoopers[0] =
-            SkBlurDrawLooper::Create(SK_ColorBLUE,
+        sk_sp<SkDrawLooper> shadowLoopers[] = {
+              SkBlurDrawLooper::Make(SK_ColorBLUE,
                                      SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(10)),
                                      SkIntToScalar(5), SkIntToScalar(10),
                                      SkBlurDrawLooper::kIgnoreTransform_BlurFlag |
                                      SkBlurDrawLooper::kOverrideColor_BlurFlag |
-                                     SkBlurDrawLooper::kHighQuality_BlurFlag);
-        SkAutoUnref aurL0(shadowLoopers[0]);
-        shadowLoopers[1] =
-            SkBlurDrawLooper::Create(SK_ColorBLUE,
+                                     SkBlurDrawLooper::kHighQuality_BlurFlag),
+              SkBlurDrawLooper::Make(SK_ColorBLUE,
                                      SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(10)),
                                      SkIntToScalar(5), SkIntToScalar(10),
                                      SkBlurDrawLooper::kIgnoreTransform_BlurFlag |
-                                     SkBlurDrawLooper::kOverrideColor_BlurFlag);
-        SkAutoUnref aurL1(shadowLoopers[1]);
-        shadowLoopers[2] =
-            SkBlurDrawLooper::Create(SK_ColorBLACK,
+                                     SkBlurDrawLooper::kOverrideColor_BlurFlag),
+              SkBlurDrawLooper::Make(SK_ColorBLACK,
                                      SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(5)),
                                      SkIntToScalar(5),
                                      SkIntToScalar(10),
                                      SkBlurDrawLooper::kIgnoreTransform_BlurFlag |
-                                     SkBlurDrawLooper::kHighQuality_BlurFlag);
-        SkAutoUnref aurL2(shadowLoopers[2]);
-        shadowLoopers[3] =
-            SkBlurDrawLooper::Create(0x7FFF0000,
+                                     SkBlurDrawLooper::kHighQuality_BlurFlag),
+              SkBlurDrawLooper::Make(0x7FFF0000,
                                      SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(5)),
                                      SkIntToScalar(-5), SkIntToScalar(-10),
                                      SkBlurDrawLooper::kIgnoreTransform_BlurFlag |
                                      SkBlurDrawLooper::kOverrideColor_BlurFlag |
-                                     SkBlurDrawLooper::kHighQuality_BlurFlag);
-        SkAutoUnref aurL3(shadowLoopers[3]);
-        shadowLoopers[4] =
-            SkBlurDrawLooper::Create(SK_ColorBLACK, SkIntToScalar(0),
+                                     SkBlurDrawLooper::kHighQuality_BlurFlag),
+            SkBlurDrawLooper::Make(SK_ColorBLACK, SkIntToScalar(0),
                                      SkIntToScalar(5), SkIntToScalar(5),
                                      SkBlurDrawLooper::kIgnoreTransform_BlurFlag |
                                      SkBlurDrawLooper::kOverrideColor_BlurFlag |
-                                     SkBlurDrawLooper::kHighQuality_BlurFlag);
-        SkAutoUnref aurL4(shadowLoopers[4]);
+                                     SkBlurDrawLooper::kHighQuality_BlurFlag),
+        };
 
         static const struct {
             SkColor fColor;