Add BoxF::ExpandTo

ui/gfx/box_f.h

 // Copyright 2013 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_BOX_F_H_
 #define UI_GFX_BOX_F_H_
 
 #include "ui/gfx/point3_f.h"
 #include "ui/gfx/vector3d_f.h"
 
@@ skipping 76 matching lines @@
 
   void set_size(float width, float height, float depth) {
     width_ = width < 0 ? 0 : width;
     height_ = height < 0 ? 0 : height;
     depth_ = depth < 0 ? 0 : depth;
   }
 
   const Point3F& origin() const { return origin_; }
   void set_origin(const Point3F& origin) { origin_ = origin; }
 
+  // Expands |this| to contain the given point, if necessary. Please note, even
+  // if |this| is empty, after the function |this| will continue to contain its
+  // |origin_|.
+  void ExpandTo(const Point3F& point);
+
  private:
+  // Expands the box to contain the two given points. It is required that each
+  // component of |min| is less than or equal to the corresponding component in
+  // |max|. Precisely, what this function does is ensure that after the function
+  // completes, |this| contains origin_, min, max, and origin_ + (width_,
+  // height_, depth_), even if the box is empty. Emptiness checks are handled in
+  // the public function Union.
+  void ExpandTo(const Point3F& min, const Point3F& max);
+
   Point3F origin_;
   float width_;
   float height_;
   float depth_;
 };
 
 GFX_EXPORT BoxF UnionBoxes(const BoxF& a, const BoxF& b);
 
 inline BoxF ScaleBox(const BoxF& b,
                      float x_scale,
@@ skipping 25 matching lines @@
               b.y() + v.y(),
               b.z() + v.z(),
               b.width(),
               b.height(),
               b.depth());
 }
 
 }  // namespace gfx
 
 #endif  // UI_GFX_BOX_F_H_