ui: Prefer +/- operators to apply offsets.

ui/gfx/rect.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.
 
 // Defines a simple integer 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 59 matching lines @@
 };
 
 inline bool operator==(const Rect& lhs, const Rect& rhs) {
   return lhs.origin() == rhs.origin() && lhs.size() == rhs.size();
 }
 
 inline bool operator!=(const Rect& lhs, const Rect& rhs) {
   return !(lhs == rhs);
 }
 
+UI_EXPORT Rect operator+(const Rect& lhs, const Vector2d& rhs);
+UI_EXPORT Rect operator-(const Rect& lhs, const Vector2d& rhs);
+
+inline Rect operator+(const Vector2d& lhs, const Rect& rhs) {
+  return rhs + lhs;
+}
+
 UI_EXPORT Rect IntersectRects(const Rect& a, const Rect& b);
 UI_EXPORT Rect UnionRects(const Rect& a, const Rect& b);
 UI_EXPORT Rect SubtractRects(const Rect& a, const Rect& b);
 
 // Constructs a rectangle with |p1| and |p2| as opposite corners.
 //
 // This could also be thought of as "the smallest rect that contains both
 // points", except that we consider points on the right/bottom edges of the
 // rect to be outside the rect.  So technically one or both points will not be
 // contained within the rect, because they will appear on one of these edges.
 UI_EXPORT Rect BoundingRect(const Point& p1, const Point& p2);
 
 #if !defined(COMPILER_MSVC)
 extern template class RectBase<Rect, Point, Size, Insets, Vector2d, int>;
 #endif
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RECT_H_