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

cc/base/math_util.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_BASE_MATH_UTIL_H_
 #define CC_BASE_MATH_UTIL_H_
 
 #include <algorithm>
 #include <cmath>
 
@@ skipping 82 matching lines @@
 
   // Background: Existing transform code does not do the right thing in
   // MapRect / MapQuad / ProjectQuad when there is a perspective projection that
   // causes one of the transformed vertices to go to w < 0. In those cases, it
   // is necessary to perform clipping in homogeneous coordinates, after applying
   // the transform, before dividing-by-w to convert to cartesian coordinates.
   //
   // These functions return the axis-aligned rect that encloses the correctly
   // clipped, transformed polygon.
   static gfx::Rect MapClippedRect(const gfx::Transform& transform,
-                                  gfx::Rect rect);
+                                  const gfx::Rect& rect);
   static gfx::RectF MapClippedRect(const gfx::Transform& transform,
                                    const gfx::RectF& rect);
   static gfx::RectF ProjectClippedRect(const gfx::Transform& transform,
                                        const gfx::RectF& rect);
 
   // Returns an array of vertices that represent the clipped polygon. After
   // returning, indexes from 0 to num_vertices_in_clipped_quad are valid in the
   // clipped_quad array. Note that num_vertices_in_clipped_quad may be zero,
   // which means the entire quad was clipped, and none of the vertices in the
   // array are valid.
@@ skipping 46 matching lines @@
                                            gfx::Vector2dF v2);
 
   // Projects the |source| vector onto |destination|. Neither vector is assumed
   // to be normalized.
   static gfx::Vector2dF ProjectVector(gfx::Vector2dF source,
                                       gfx::Vector2dF destination);
 
   // Conversion to value.
   static scoped_ptr<base::Value> AsValue(gfx::Size s);
   static scoped_ptr<base::Value> AsValue(gfx::SizeF s);
-  static scoped_ptr<base::Value> AsValue(gfx::Rect r);
+  static scoped_ptr<base::Value> AsValue(const gfx::Rect& r);
   static bool FromValue(const base::Value*, gfx::Rect* out_rect);
   static scoped_ptr<base::Value> AsValue(gfx::PointF q);
   static scoped_ptr<base::Value> AsValue(const gfx::QuadF& q);
   static scoped_ptr<base::Value> AsValue(const gfx::RectF& rect);
   static scoped_ptr<base::Value> AsValue(const gfx::Transform& transform);
   static scoped_ptr<base::Value> AsValue(const gfx::BoxF& box);
 
   // Returns a base::Value representation of the floating point value.
   // If the value is inf, returns max double/float representation.
   static scoped_ptr<base::Value> AsValueSafely(double value);
   static scoped_ptr<base::Value> AsValueSafely(float value);
 };
 
 }  // namespace cc
 
 #endif  // CC_BASE_MATH_UTIL_H_