Use SkSafeRef when claiming a ref on the SkImageFilter at the WebKit API boundary.

Avoids a NULL deref when then image filter is NULL.

BUG=wkb.ug/103990
TBR=jamesr
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/11308354

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@171014 0039d316-1c4b-4281-b951-d872f2087c98

webkit/compositor_bindings/web_layer_impl.cc

@@ -241,7 +241,7 @@ void WebLayerImpl::setBackgroundFilters(const WebFilterOperations& filters)
 
 void WebLayerImpl::setFilter(SkImageFilter* filter)
 {
-    filter->ref(); // Claim a reference for the compositor.
+    SkSafeRef(filter); // Claim a reference for the compositor.
     m_layer->setFilter(skia::AdoptRef(filter));
 }