[#5] Pass gfx structs by const ref (gfx::Vector2dF)

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 138 matching lines @@
   // scale_inner_rect has to scale_outer_rect. scale_inner_rect should be
   // contained within scale_outer_rect, and likewise the rectangle that is
   // returned will be within input_outer_rect at a similar relative, scaled
   // position.
   static gfx::RectF ScaleRectProportional(const gfx::RectF& input_outer_rect,
                                           const gfx::RectF& scale_outer_rect,
                                           const gfx::RectF& scale_inner_rect);
 
   // Returns the smallest angle between the given two vectors in degrees.
   // Neither vector is assumed to be normalized.
-  static float SmallestAngleBetweenVectors(gfx::Vector2dF v1,
-                                           gfx::Vector2dF v2);
+  static float SmallestAngleBetweenVectors(const gfx::Vector2dF& v1,
+                                           const 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);
+  static gfx::Vector2dF ProjectVector(const gfx::Vector2dF& source,
+                                      const gfx::Vector2dF& destination);
 
   // Conversion to value.
   static scoped_ptr<base::Value> AsValue(gfx::Size s);
   static scoped_ptr<base::Value> AsValue(const gfx::SizeF& s);
   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(const 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_