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

cc/layer_tree_host_impl.cc

Index: cc/layer_tree_host_impl.cc
diff --git a/cc/layer_tree_host_impl.cc b/cc/layer_tree_host_impl.cc
index 2426e01cfdc335e0f63345611f9a2d1923f1c985..196ba6330761aeda440c5ff7d6eed7162241bd94 100644
--- a/cc/layer_tree_host_impl.cc
+++ b/cc/layer_tree_host_impl.cc
@@ -359,7 +359,7 @@ void LayerTreeHostImpl::trackDamageForAllSurfaces(LayerImpl* rootDrawLayer, cons
         LayerImpl* renderSurfaceLayer = renderSurfaceLayerList[surfaceIndex];
         RenderSurfaceImpl* renderSurface = renderSurfaceLayer->renderSurface();
         DCHECK(renderSurface);
-        renderSurface->damageTracker()->updateDamageTrackingState(renderSurface->layerList(), renderSurfaceLayer->id(), renderSurface->surfacePropertyChangedOnlyFromDescendant(), renderSurface->contentRect(), renderSurfaceLayer->maskLayer(), renderSurfaceLayer->filters(), renderSurfaceLayer->filter());
+        renderSurface->damageTracker()->updateDamageTrackingState(renderSurface->layerList(), renderSurfaceLayer->id(), renderSurface->surfacePropertyChangedOnlyFromDescendant(), renderSurface->contentRect(), renderSurfaceLayer->maskLayer(), renderSurfaceLayer->filters(), renderSurfaceLayer->filter().get());
     }
 }