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

cc/surfaces/surface_aggregator_test_helpers.cc

 // 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.
 
 #include "cc/surfaces/surface_aggregator_test_helpers.h"
 
 #include "base/format_macros.h"
 #include "base/strings/stringprintf.h"
 #include "cc/layers/append_quads_data.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/delegated_frame_data.h"
 #include "cc/quads/render_pass_draw_quad.h"
 #include "cc/quads/shared_quad_state.h"
 #include "cc/quads/solid_color_draw_quad.h"
 #include "cc/quads/surface_draw_quad.h"
 #include "cc/surfaces/surface.h"
 #include "cc/test/render_pass_test_common.h"
 #include "cc/test/render_pass_test_utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/skia/include/core/SkXfermode.h"
 
 namespace cc {
 namespace test {
 
 void AddTestSurfaceQuad(TestRenderPass* pass,
                         const gfx::Size& surface_size,
-                        int surface_id) {
+                        SurfaceId surface_id) {
   gfx::Transform content_to_target_transform;
   gfx::Size content_bounds = surface_size;
   gfx::Rect visible_content_rect = gfx::Rect(surface_size);
   gfx::Rect clip_rect = gfx::Rect(surface_size);
   bool is_clipped = false;
   float opacity = 1.0;
   SkXfermode::Mode blend_mode = SkXfermode::kSrcOver_Mode;
 
   SharedQuadState* shared_quad_state = pass->CreateAndAppendSharedQuadState();
   shared_quad_state->SetAll(content_to_target_transform,
@@ skipping 123 matching lines @@
   delegated_frame_data->render_pass_list.push_back(pass.Pass());
 
   scoped_ptr<CompositorFrame> child_frame(new CompositorFrame);
   child_frame->delegated_frame_data = delegated_frame_data.Pass();
 
   surface->QueueFrame(child_frame.Pass());
 }
 
 }  // namespace test
 }  // namespace cc