fix leak in new createproc

BUG=skia:
R=caryclark@google.com, mike@reedtribe.org, mtklein@google.com

Author: reed@chromium.org

Review URL: https://codereview.chromium.org/461253007
diff --git a/src/effects/SkColorFilterImageFilter.cpp b/src/effects/SkColorFilterImageFilter.cpp
index 2a7cc31..0087627 100755
--- a/src/effects/SkColorFilterImageFilter.cpp
+++ b/src/effects/SkColorFilterImageFilter.cpp
@@ -92,7 +92,8 @@
 
 SkFlattenable* SkColorFilterImageFilter::CreateProc(SkReadBuffer& buffer) {
     SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);
-    return Create(buffer.readColorFilter(), common.getInput(0), &common.cropRect());
+    SkAutoTUnref<SkColorFilter> cf(buffer.readColorFilter());
+    return Create(cf, common.getInput(0), &common.cropRect());
 }
 
 void SkColorFilterImageFilter::flatten(SkWriteBuffer& buffer) const {