Remove use of SkSmallAllocator from all Loopers.

R=reed@google.com

Change-Id: I22b140ee8e12900de13bc623adb30b5fca3051f9
Reviewed-on: https://skia-review.googlesource.com/7658
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Herb Derby <herb@google.com>
diff --git a/include/effects/SkLayerDrawLooper.h b/include/effects/SkLayerDrawLooper.h
index df112c8..c0a9534 100644
--- a/include/effects/SkLayerDrawLooper.h
+++ b/include/effects/SkLayerDrawLooper.h
@@ -71,9 +71,7 @@
         LayerInfo();
     };
 
-    SkDrawLooper::Context* createContext(SkCanvas*, void* storage) const override;
-
-    size_t contextSize() const override { return sizeof(LayerDrawLooperContext); }
+    SkDrawLooper::Context* makeContext(SkCanvas*, SkArenaAlloc*) const override;
 
     bool asABlurShadow(BlurShadowRec* rec) const override;