[WIP] cc: Plumb SurfaceId from clients

cc/trees/layer_tree_host.h

 // Copyright 2011 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_TREES_LAYER_TREE_HOST_H_
 #define CC_TREES_LAYER_TREE_HOST_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 321 matching lines @@
   void RemoveSwapPromiseMonitor(SwapPromiseMonitor* monitor);
 
   // Call this function when you expect there to be a swap buffer.
   // See swap_promise.h for how to use SwapPromise.
   void QueueSwapPromise(std::unique_ptr<SwapPromise> swap_promise);
 
   void BreakSwapPromises(SwapPromise::DidNotSwapReason reason);
 
   size_t num_queued_swap_promises() const { return swap_promise_list_.size(); }
 
+  uint32_t surface_client_id() const { return surface_client_id_; }
   void set_surface_client_id(uint32_t client_id);
   SurfaceSequence CreateSurfaceSequence();
 
   PropertyTrees* property_trees() { return &property_trees_; }
   bool needs_meta_info_recomputation() {
     return needs_meta_info_recomputation_;
   }
 
   void SetLayerTreeMutator(std::unique_ptr<LayerTreeMutator> mutator);
 
@@ skipping 254 matching lines @@
   uint32_t surface_client_id_;
   uint32_t next_surface_sequence_;
   uint32_t num_consecutive_frames_suitable_for_gpu_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_