Add support for converting cc::FilterOperations into an SkImageFilter

cc/layers/delegated_renderer_layer_impl_unittest.cc

Index: cc/layers/delegated_renderer_layer_impl_unittest.cc
diff --git a/cc/layers/delegated_renderer_layer_impl_unittest.cc b/cc/layers/delegated_renderer_layer_impl_unittest.cc
index 401ac3cd67b54a10ea5d798be224feaa6000648b..710ef90e32392eadef44309c395880c318538d8e 100644
--- a/cc/layers/delegated_renderer_layer_impl_unittest.cc
+++ b/cc/layers/delegated_renderer_layer_impl_unittest.cc
@@ -549,7 +549,6 @@ class DelegatedRendererLayerImplTestTransform
         child_pass_rect,  // contents_changed_since_last_frame
         gfx::RectF(),  // mask_uv_rect
         FilterOperations(),  // filters
-        skia::RefPtr<SkImageFilter>(),  // filter
         FilterOperations());  // background_filters
     quad_sink.Append(render_pass_quad.PassAs<DrawQuad>(), &data);
 
@@ -951,7 +950,6 @@ class DelegatedRendererLayerImplTestClip
         child_pass_rect,  // contents_changed_since_last_frame
         gfx::RectF(),  // mask_uv_rect
         FilterOperations(),  // filters
-        skia::RefPtr<SkImageFilter>(),  // filter
         FilterOperations());  // background_filters
     quad_sink.Append(render_pass_quad.PassAs<DrawQuad>(), &data);