Add support for converting cc::FilterOperations into an SkImageFilter

cc/trees/occlusion_tracker.cc

Index: cc/trees/occlusion_tracker.cc
diff --git a/cc/trees/occlusion_tracker.cc b/cc/trees/occlusion_tracker.cc
index 9fc26da566700ce9b46cb88974730ba722a6b155..7bcac0971e06658b1b7133e24dce7c2a7c9ba1dc 100644
--- a/cc/trees/occlusion_tracker.cc
+++ b/cc/trees/occlusion_tracker.cc
@@ -240,7 +240,7 @@ void OcclusionTrackerBase<LayerType, RenderSurfaceType>::FinishedRenderTarget(
       surface->draw_opacity() < 1 ||
       target_is_only_for_copy_request ||
       finished_target->filters().HasFilterThatAffectsOpacity() ||
-      finished_target->filter()) {
+      finished_target->filters().HasReferenceFilter()) {

[danakj, 2013/09/09 22:04:50]

can't this just be removed?

[ajuma, 2013/09/10 21:17:58]

Yes, removed this and moved the TODO from above to
FilterOperations::HasFilterThatAffectsOpacity.

     stack_.back().occlusion_from_outside_target.Clear();
     stack_.back().occlusion_from_inside_target.Clear();
   } else if (!SurfaceTransformsToTargetKnown(surface)) {