Make gfx::Rect class operations consistently mutate the class they are called on.

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 82 matching lines @@
     return Contains(point.x(), point.y());
   }
 
   // Returns true if this rectangle contains the specified rectangle.
   bool Contains(const Class& rect) const;
 
   // Returns true if this rectangle intersects the specified rectangle.
   bool Intersects(const Class& rect) const;
 
   // Computes the intersection of this rectangle with the given rectangle.
-  Class Intersect(const Class& rect) const WARN_UNUSED_RESULT;
+  void Intersect(const Class& rect);
 
   // Computes the union of this rectangle with the given rectangle.  The union
   // is the smallest rectangle containing both rectangles.
-  Class Union(const Class& rect) const WARN_UNUSED_RESULT;
+  void Union(const Class& rect);
 
   // Computes the rectangle resulting from subtracting |rect| from |this|.  If
   // |rect| does not intersect completely in either the x- or y-direction, then
-  // |*this| is returned.  If |rect| contains |this|, then an empty Rect is
-  // returned.
-  Class Subtract(const Class& rect) const WARN_UNUSED_RESULT;
+  // |*this| does not change.  If |rect| contains |this|, then an empty Rect is
+  // the result.
+  void Subtract(const Class& rect);
 
   // Fits as much of the receiving rectangle into the supplied rectangle as
-  // possible, returning the result. For example, if the receiver had
+  // possible, becoming the result. For example, if the receiver had
   // a x-location of 2 and a width of 4, and the supplied rectangle had
   // an x-location of 0 with a width of 5, the returned rectangle would have
   // an x-location of 1 with a width of 4.
-  Class AdjustToFit(const Class& rect) const WARN_UNUSED_RESULT;
+  void AdjustToFit(const Class& rect);
 
   // Returns the center of this rectangle.
   PointClass CenterPoint() const;
 
-  // Return a rectangle that has the same center point but with a size capped
+  // Becomes a rectangle that has the same center point but with a size capped
   // at given |size|.
-  Class Center(const SizeClass& size) const WARN_UNUSED_RESULT;
+  void ClampToCenteredSize(const SizeClass& size);
 
   // Splits |this| in two halves, |left_half| and |right_half|.
   void SplitVertically(Class* left_half, Class* right_half) const;
 
   // Returns true if this rectangle shares an entire edge (i.e., same width or
   // same height) with the given rectangle, and the rectangles do not overlap.
   bool SharesEdgeWith(const Class& rect) const;
 
  protected:
   RectBase(const PointClass& origin, const SizeClass& size);
   explicit RectBase(const SizeClass& size);
   explicit RectBase(const PointClass& origin);
   // Destructor is intentionally made non virtual and protected.
   // Do not make this public.
   ~RectBase();
 
  private:
   PointClass origin_;
   SizeClass size_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RECT_BASE_H_