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

ui/views/layout/box_layout.cc

 // 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.
 
 #include "ui/views/layout/box_layout.h"
 
 #include "ui/gfx/insets.h"
 #include "ui/gfx/rect.h"
 #include "ui/views/view.h"
 
@@ skipping 54 matching lines @@
       gfx::Rect bounds(x, y, child_area.width(), child_area.height());
       gfx::Size size(child->GetPreferredSize());
       if (orientation_ == kHorizontal) {
         bounds.set_width(size.width() + padding);
         x += size.width() + between_child_spacing_ + padding;
       } else {
         bounds.set_height(size.height() + padding);
         y += size.height() + between_child_spacing_ + padding;
       }
       // Clamp child view bounds to |child_area|.
-      child->SetBoundsRect(bounds.Intersect(child_area));
+      bounds.Intersect(child_area);
+      child->SetBoundsRect(bounds);
     }
   }
 }
 
 gfx::Size BoxLayout::GetPreferredSize(View* host) {
   gfx::Rect bounds;
   int position = 0;
   for (int i = 0; i < host->child_count(); ++i) {
     View* child = host->child_at(i);
     if (child->visible()) {
       gfx::Size size(child->GetPreferredSize());
       if (orientation_ == kHorizontal) {
         gfx::Rect child_bounds(position, 0, size.width(), size.height());
-        bounds = bounds.Union(child_bounds);
+        bounds.Union(child_bounds);
         position += size.width();
       } else {
         gfx::Rect child_bounds(0, position, size.width(), size.height());
-        bounds = bounds.Union(child_bounds);
+        bounds.Union(child_bounds);
         position += size.height();
       }
       position += between_child_spacing_;
     }
   }
   gfx::Insets insets(host->GetInsets());
   return gfx::Size(
       bounds.width() + insets.width() + 2 * inside_border_horizontal_spacing_,
       bounds.height() + insets.height() + 2 * inside_border_vertical_spacing_);
 }
 
 } // namespace views