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

cc/quads/surface_draw_quad.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_QUADS_SURFACE_DRAW_QUAD_H_
 #define CC_QUADS_SURFACE_DRAW_QUAD_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "cc/quads/draw_quad.h"
+#include "cc/surfaces/surface_id.h"
 
 namespace cc {
 
 class CC_EXPORT SurfaceDrawQuad : public DrawQuad {
  public:
   static scoped_ptr<SurfaceDrawQuad> Create();
 
   void SetNew(const SharedQuadState* shared_quad_state,
               const gfx::Rect& rect,
               const gfx::Rect& visible_rect,
-              int surface_id);
+              SurfaceId surface_id);
 
   void SetAll(const SharedQuadState* shared_quad_state,
               const gfx::Rect& rect,
               const gfx::Rect& opaque_rect,
               const gfx::Rect& visible_rect,
               bool needs_blending,
-              int surface_id);
+              SurfaceId surface_id);
 
-  int surface_id;
+  SurfaceId surface_id;
 
   virtual void IterateResources(const ResourceIteratorCallback& callback)
       OVERRIDE;
 
   static const SurfaceDrawQuad* MaterialCast(const DrawQuad* quad);
 
  private:
   SurfaceDrawQuad();
   virtual void ExtendValue(base::DictionaryValue* value) const OVERRIDE;
 };
 
 }  // namespace cc
 
 #endif  // CC_QUADS_SURFACE_DRAW_QUAD_H_