Use a struct for cc::Surface ids for more type safety

cc/surfaces/surface_aggregator.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_AGGREGATOR_H_
 #define CC_SURFACES_SURFACE_AGGREGATOR_H_
 
 #include <set>
 
 #include "base/containers/scoped_ptr_hash_map.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/quads/render_pass.h"
+#include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surfaces_export.h"
 
 namespace cc {
 
 class CompositorFrame;
 class DelegatedFrameData;
 class SurfaceDrawQuad;
 class SurfaceManager;
 
 class CC_SURFACES_EXPORT SurfaceAggregator {
  public:
   explicit SurfaceAggregator(SurfaceManager* manager);
   ~SurfaceAggregator();
 
-  scoped_ptr<CompositorFrame> Aggregate(int surface_id);
+  scoped_ptr<CompositorFrame> Aggregate(SurfaceId surface_id);
 
  private:
-  DelegatedFrameData* GetReferencedDataForSurfaceID(int surface_id);
+  DelegatedFrameData* GetReferencedDataForSurfaceId(SurfaceId surface_id);
   RenderPass::Id RemapPassId(RenderPass::Id surface_local_pass_id,
                              int surface_id);
 
   void HandleSurfaceQuad(const SurfaceDrawQuad* surface_quad,
                          RenderPass* dest_pass);
   void CopySharedQuadState(const SharedQuadState* source_sqs,
                            const gfx::Transform& content_to_target_transform,
                            RenderPass* dest_render_pass);
   void CopyQuadsToPass(const QuadList& source_quad_list,
                        const SharedQuadStateList& source_shared_quad_state_list,
@@ skipping 19 matching lines @@
 
   // This is the pass list for the aggregated frame.
   RenderPassList* dest_pass_list_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceAggregator);
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_AGGREGATOR_H_