Release resources from SurfaceAggregator when new frame arrives.

cc/surfaces/surface_aggregator.cc

Index: cc/surfaces/surface_aggregator.cc
diff --git a/cc/surfaces/surface_aggregator.cc b/cc/surfaces/surface_aggregator.cc
index 2334d141e28557be84fb1e9199016ad4788b6652..4c4408484e254c3009c05fe15ed33ba4e9b43210 100644
--- a/cc/surfaces/surface_aggregator.cc
+++ b/cc/surfaces/surface_aggregator.cc
@@ -438,4 +438,13 @@ scoped_ptr<CompositorFrame> SurfaceAggregator::Aggregate(SurfaceId surface_id) {
   return frame.Pass();
 }
 
+void SurfaceAggregator::ReleaseResources(SurfaceId surface_id) {
+  SurfaceToResourceChildIdMap::iterator it =
+      surface_id_to_resource_child_id_.find(surface_id);
+  if (it != surface_id_to_resource_child_id_.end()) {
+    provider_->DestroyChild(it->second);
+    surface_id_to_resource_child_id_.erase(it);
+  }
+}
+
 }  // namespace cc