[#2] Pass gfx structs by const ref (gfx::Rect, gfx::RectF)

cc/test/occlusion_tracker_test_common.h

 // Copyright 2012 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_OCCLUSION_TRACKER_TEST_COMMON_H_
 #define CC_TEST_OCCLUSION_TRACKER_TEST_COMMON_H_
 
 #include "cc/layers/render_surface.h"
 #include "cc/layers/render_surface_impl.h"
 #include "cc/trees/occlusion_tracker.h"
 
 namespace cc {
 
 // A subclass to expose the total current occlusion.
 template <typename LayerType, typename RenderSurfaceType>
 class TestOcclusionTrackerBase
     : public OcclusionTrackerBase<LayerType, RenderSurfaceType> {
  public:
-  TestOcclusionTrackerBase(gfx::Rect screen_scissor_rect,
+  TestOcclusionTrackerBase(const gfx::Rect& screen_scissor_rect,
                            bool record_metrics_for_frame)
       : OcclusionTrackerBase<LayerType, RenderSurfaceType>(
             screen_scissor_rect,
             record_metrics_for_frame) {}
 
   Region occlusion_from_inside_target() const {
     return OcclusionTrackerBase<LayerType, RenderSurfaceType>::stack_.back().
         occlusion_from_inside_target;
   }
   Region occlusion_from_outside_target() const {
@@ skipping 11 matching lines @@
   }
 };
 
 typedef TestOcclusionTrackerBase<Layer, RenderSurface> TestOcclusionTracker;
 typedef TestOcclusionTrackerBase<LayerImpl, RenderSurfaceImpl>
     TestOcclusionTrackerImpl;
 
 }  // namespace cc
 
 #endif  // CC_TEST_OCCLUSION_TRACKER_TEST_COMMON_H_