Add skia::RefPtr class to wrap ref counted classes from Skia.

content/common/cc_messages.cc

Index: content/common/cc_messages.cc
diff --git a/content/common/cc_messages.cc b/content/common/cc_messages.cc
index 166e77a168a2f257ee7b8549de34a7290212ea5f..127bafd64efa3d9e4873daebd76d4a075f000b40 100644
--- a/content/common/cc_messages.cc
+++ b/content/common/cc_messages.cc
@@ -414,6 +414,7 @@ bool ParamTraits<cc::RenderPass>::Read(
   bool has_transparent_background;
   bool has_occlusion_from_outside_target_surface;
   WebKit::WebFilterOperations filters;
+  skia::RefPtr<SkImageFilter> filter;
   WebKit::WebFilterOperations background_filters;
   size_t shared_quad_state_list_size;
   size_t quad_list_size;
@@ -437,7 +438,7 @@ bool ParamTraits<cc::RenderPass>::Read(
             has_transparent_background,
             has_occlusion_from_outside_target_surface,
             filters,
-            NULL, // TODO(danakj): filter isn't being serialized.
+            filter, // TODO(danakj): filter isn't being serialized.
             background_filters);
 
   for (size_t i = 0; i < shared_quad_state_list_size; ++i) {