Make various gfx classes more amenable to use as compile-time constants.

ui/gfx/geometry/point_f.h

 // Copyright (c) 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 UI_GFX_GEOMETRY_POINT_F_H_
 #define UI_GFX_GEOMETRY_POINT_F_H_
 
 #include <iosfwd>
 #include <string>
 #include <tuple>
 
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/vector2d_f.h"
 #include "ui/gfx/gfx_export.h"
 
 namespace gfx {
 
 // A floating version of gfx::Point.
 class GFX_EXPORT PointF {
  public:
-  PointF() : x_(0.f), y_(0.f) {}
-  PointF(float x, float y) : x_(x), y_(y) {}
-  ~PointF() {}
+  constexpr PointF() : x_(0.f), y_(0.f) {}
+  constexpr PointF(float x, float y) : x_(x), y_(y) {}
 
-  explicit PointF(const Point& p)
+  constexpr explicit PointF(const Point& p)
       : PointF(static_cast<float>(p.x()), static_cast<float>(p.y())) {}
 
-  float x() const { return x_; }
-  float y() const { return y_; }
+  constexpr float x() const { return x_; }
+  constexpr float y() const { return y_; }
   void set_x(float x) { x_ = x; }
   void set_y(float y) { y_ = y; }
 
   void SetPoint(float x, float y) {
     x_ = x;
     y_ = y;
   }
 
   void Offset(float delta_x, float delta_y) {
     x_ += delta_x;
@@ skipping 78 matching lines @@
 }
 
 // This is declared here for use in gtest-based unit tests but is defined in
 // the gfx_test_support target. Depend on that to use this in your unit test.
 // This should not be used in production code - call ToString() instead.
 void PrintTo(const PointF& point, ::std::ostream* os);
 
 }  // namespace gfx
 
 #endif  // UI_GFX_GEOMETRY_POINT_F_H_