Update from chromium https://crrev.com/304586

cc/surfaces/surface_aggregator.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/surfaces/surface_aggregator.h"
 
 #include <map>
 
 #include "base/bind.h"
 #include "base/containers/hash_tables.h"
@@ skipping 363 matching lines @@
     CopyQuadsToPass(source.quad_list,
                     source.shared_quad_state_list,
                     gfx::Transform(),
                     copy_pass.get(),
                     surface->surface_id());
 
     dest_pass_list_->push_back(copy_pass.Pass());
   }
 }
 
+void SurfaceAggregator::RemoveUnreferencedChildren() {
+  for (const auto& surface : previous_contained_surfaces_) {
+    if (!contained_surfaces_.count(surface.first)) {
+      SurfaceToResourceChildIdMap::iterator it =
+          surface_id_to_resource_child_id_.find(surface.first);
+      if (it != surface_id_to_resource_child_id_.end()) {
+        provider_->DestroyChild(it->second);
+        surface_id_to_resource_child_id_.erase(it);
+      }
+    }
+  }
+}
+
 scoped_ptr<CompositorFrame> SurfaceAggregator::Aggregate(SurfaceId surface_id) {
   Surface* surface = manager_->GetSurfaceForId(surface_id);
   DCHECK(surface);
   contained_surfaces_[surface_id] = surface->frame_index();
   const CompositorFrame* root_surface_frame = surface->GetEligibleFrame();
   if (!root_surface_frame)
     return nullptr;
   TRACE_EVENT0("cc", "SurfaceAggregator::Aggregate");
 
   scoped_ptr<CompositorFrame> frame(new CompositorFrame);
   frame->delegated_frame_data = make_scoped_ptr(new DelegatedFrameData);
 
   DCHECK(root_surface_frame->delegated_frame_data);
 
   SurfaceSet::iterator it = referenced_surfaces_.insert(surface_id).first;
 
   dest_resource_list_ = &frame->delegated_frame_data->resource_list;
   dest_pass_list_ = &frame->delegated_frame_data->render_pass_list;
 
   CopyPasses(root_surface_frame->delegated_frame_data.get(), surface);
 
   referenced_surfaces_.erase(it);
   DCHECK(referenced_surfaces_.empty());
 
   dest_pass_list_ = NULL;
+  RemoveUnreferencedChildren();
   contained_surfaces_.swap(previous_contained_surfaces_);
   contained_surfaces_.clear();
 
   for (SurfaceIndexMap::iterator it = previous_contained_surfaces_.begin();
        it != previous_contained_surfaces_.end();
        ++it) {
     Surface* surface = manager_->GetSurfaceForId(it->first);
     if (surface)
       surface->TakeLatencyInfo(&frame->metadata.latency_info);
   }
 
   // TODO(jamesr): Aggregate all resource references into the returned frame's
   // resource list.
 
   return frame.Pass();
 }
 
 }  // namespace cc