ui: Add methods to Rect classes to get points at each of the rect's corners.

ui/gfx/rect_base.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.
 
 // A template for a simple rectangle class.  The containment semantics
 // are array-like; that is, the coordinate (x, y) is considered to be
 // contained by the rectangle, but the coordinate (x + width, y) is not.
 // The class will happily let you create malformed rectangles (that is,
 // rectangles with negative width and/or height), but there will be assertions
 // in the operations (such as Contains()) to complain in this case.
@@ skipping 29 matching lines @@
 
   const PointClass& origin() const { return origin_; }
   void set_origin(const PointClass& origin) { origin_ = origin; }
 
   const SizeClass& size() const { return size_; }
   void set_size(const SizeClass& size) { size_ = size; }
 
   Type right() const { return x() + width(); }
   Type bottom() const { return y() + height(); }
 
+  PointClass top_right() const { return PointClass(right(), y()); }
+  PointClass bottom_left() const { return PointClass(x(), bottom()); }
+  PointClass bottom_right() const { return PointClass(right(), bottom()); }
+
   VectorClass OffsetFromOrigin() const {
     return VectorClass(x(), y());
   }
 
   void SetRect(Type x, Type y, Type width, Type height);
 
   // Shrink the rectangle by a horizontal and vertical distance on all sides.
   void Inset(Type horizontal, Type vertical) {
     Inset(horizontal, vertical, horizontal, vertical);
   }
@@ skipping 89 matching lines @@
   ~RectBase();
 
  private:
   PointClass origin_;
   SizeClass size_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RECT_BASE_H_