Enqueuing new frames in a Surface should cause Displays to reaggregate it

cc/surfaces/surface_aggregator.h

Index: cc/surfaces/surface_aggregator.h
diff --git a/cc/surfaces/surface_aggregator.h b/cc/surfaces/surface_aggregator.h
index ec36b4be5976b84bbcec2baa317300af318a4dc9..de9a6d68f144982e9ad30c4e754cd482c143d47a 100644
--- a/cc/surfaces/surface_aggregator.h
+++ b/cc/surfaces/surface_aggregator.h
@@ -29,7 +29,9 @@ class CC_SURFACES_EXPORT SurfaceAggregator {
   SurfaceAggregator(SurfaceManager* manager, ResourceProvider* provider);
   ~SurfaceAggregator();
 
-  scoped_ptr<CompositorFrame> Aggregate(SurfaceId surface_id);
+  scoped_ptr<CompositorFrame> Aggregate(
+      SurfaceId surface_id,
+      std::set<SurfaceId>* contained_surfaces);
 
  private:
   RenderPass::Id RemapPassId(RenderPass::Id surface_local_pass_id,
@@ -72,6 +74,9 @@ class CC_SURFACES_EXPORT SurfaceAggregator {
   typedef std::set<SurfaceId> SurfaceSet;
   SurfaceSet referenced_surfaces_;
 
+  // This is the set of surfaces that were used in the last draw.
+  SurfaceSet* contained_surfaces_;
+
   // This is the pass list for the aggregated frame.
   RenderPassList* dest_pass_list_;