Make the SkPathRef GenIDChangeListener ref counted

Bug: skia:
Change-Id: I2780e3fc76153373b4efca6059ded82f4f749325
Reviewed-on: https://skia-review.googlesource.com/133502
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
diff --git a/src/gpu/GrSoftwarePathRenderer.cpp b/src/gpu/GrSoftwarePathRenderer.cpp
index 15ea55d..bcd9874 100644
--- a/src/gpu/GrSoftwarePathRenderer.cpp
+++ b/src/gpu/GrSoftwarePathRenderer.cpp
@@ -363,7 +363,7 @@
         if (useCache) {
             SkASSERT(proxy->origin() == kTopLeft_GrSurfaceOrigin);
             fProxyProvider->assignUniqueKeyToProxy(maskKey, proxy.get());
-            args.fShape->addGenIDChangeListener(new PathInvalidator(maskKey));
+            args.fShape->addGenIDChangeListener(sk_make_sp<PathInvalidator>(maskKey));
         }
     }
     if (inverseFilled) {