Decouple FrameSink Hierarchy registration from SurfaceFactoryClient registration

cc/surfaces/surface_manager.h

 // 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.
 
 #ifndef CC_SURFACES_SURFACE_MANAGER_H_
 #define CC_SURFACES_SURFACE_MANAGER_H_
 
 #include <stdint.h>
 
 #include <list>
@@ skipping 233 matching lines @@
   // this set, any remaining sequences with that namespace are considered
   // satisfied.
   std::unordered_set<FrameSinkId, FrameSinkIdHash> valid_frame_sink_ids_;
 
   // Begin frame source routing. Both BeginFrameSource and SurfaceFactoryClient
   // pointers guaranteed alive by callers until unregistered.
   struct FrameSinkSourceMapping {
     FrameSinkSourceMapping();
     FrameSinkSourceMapping(const FrameSinkSourceMapping& other);
     ~FrameSinkSourceMapping();
-    bool is_empty() const { return !client && children.empty(); }
-    // The client that's responsible for creating this namespace.  Never null.
-    SurfaceFactoryClient* client;
+    bool has_children() const { return !children.empty(); }
     // The currently assigned begin frame source for this client.
     BeginFrameSource* source;
     // This represents a dag of parent -> children mapping.
     std::vector<FrameSinkId> children;
   };
+
+  std::unordered_map<FrameSinkId, SurfaceFactoryClient*, FrameSinkIdHash>
+      clients_;
+
   std::unordered_map<FrameSinkId, FrameSinkSourceMapping, FrameSinkIdHash>
       frame_sink_source_map_;
 
   // Tracks references from the child surface to parent surface. If there are
   // zero entries in the set for a SurfaceId then nothing is referencing the
   // surface and it can be garbage collected.
   std::unordered_map<SurfaceId, SurfaceIdSet, SurfaceIdHash>
       child_to_parent_refs_;
   // Tracks references from the parent surface to child surface. Is the inverse
   // of |child_to_parent_refs_|.
@@ skipping 34 matching lines @@
   std::unique_ptr<SurfaceDependencyTracker> dependency_tracker_;
 
   base::WeakPtrFactory<SurfaceManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceManager);
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_MANAGER_H_