Reusing base::IdType<...> to implement SurfaceId.

cc/test/surface_aggregator_test_helpers.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_TEST_SURFACE_AGGREGATOR_TEST_HELPERS_H_
 #define CC_TEST_SURFACE_AGGREGATOR_TEST_HELPERS_H_
 
 #include <vector>
 
 #include "cc/quads/draw_quad.h"
 #include "cc/quads/render_pass_id.h"
 #include "cc/surfaces/surface_id.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace cc {
 
 class RenderPass;
 class Surface;
 class TestRenderPass;
 
 typedef std::vector<scoped_ptr<RenderPass>> RenderPassList;
 
 namespace test {
 
 struct Quad {
-  static Quad SolidColorQuad(SkColor color) {
-    Quad quad;
-    quad.material = DrawQuad::SOLID_COLOR;
-    quad.color = color;
-    return quad;
-  }
-
-  static Quad SurfaceQuad(SurfaceId surface_id, float opacity) {
-    Quad quad;
-    quad.material = DrawQuad::SURFACE_CONTENT;
-    quad.opacity = opacity;
-    quad.surface_id = surface_id;
-    return quad;
-  }
-
-  static Quad RenderPassQuad(RenderPassId id) {
-    Quad quad;
-    quad.material = DrawQuad::RENDER_PASS;
-    quad.render_pass_id = id;
-    return quad;
-  }
+  static Quad SolidColorQuad(SkColor color);
+  static Quad SurfaceQuad(SurfaceId surface_id, float opacity);
+  static Quad RenderPassQuad(RenderPassId id);
 
   DrawQuad::Material material;
   // Set when material==DrawQuad::SURFACE_CONTENT.
   SurfaceId surface_id;
   float opacity;
   // Set when material==DrawQuad::SOLID_COLOR.
   SkColor color;
   // Set when material==DrawQuad::RENDER_PASS.
   RenderPassId render_pass_id;
 
  private:
-  Quad() : material(DrawQuad::INVALID), opacity(1.f), color(SK_ColorWHITE) {}
+  Quad();
 };
 
 struct Pass {
   Pass(Quad* quads, size_t quad_count, RenderPassId id)
       : quads(quads), quad_count(quad_count), id(id) {}
   Pass(Quad* quads, size_t quad_count)
       : quads(quads), quad_count(quad_count), id(1, 1) {}
 
   Quad* quads;
   size_t quad_count;
@@ skipping 16 matching lines @@
 void TestPassMatchesExpectations(Pass expected_pass, const RenderPass* pass);
 
 void TestPassesMatchExpectations(Pass* expected_passes,
                                  size_t expected_pass_count,
                                  const RenderPassList* passes);
 
 }  // namespace test
 }  // namespace cc
 
 #endif  // CC_TEST_SURFACE_AGGREGATOR_TEST_HELPERS_H_