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

ash/system/tray/tray_views.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 "ash/system/tray/tray_views.h"
 
 #include "ash/system/tray/tray_constants.h"
 #include "ash/system/tray/tray_item_view.h"
 #include "grit/ash_resources.h"
 #include "grit/ash_strings.h"
@@ skipping 604 matching lines @@
   gfx::Rect content_bounds = GetContentsBounds();
   if (content_bounds.IsEmpty())
     return;
   if (!button_container_) {
     content_->SetBoundsRect(GetContentsBounds());
     return;
   }
 
   gfx::Rect bounds(button_container_->GetPreferredSize());
   bounds.set_height(content_bounds.height());
-  bounds = content_bounds.Center(bounds.size());
-  bounds.set_x(content_bounds.width() - bounds.width());
-  button_container_->SetBoundsRect(bounds);
+  gfx::Rect container_bounds = content_bounds;
+  container_bounds.ClampToCenteredSize(bounds.size());
+  container_bounds.set_x(content_bounds.width() - bounds.width());
+  button_container_->SetBoundsRect(container_bounds);
 
   bounds = content_->bounds();
   bounds.set_width(button_container_->x());
   content_->SetBoundsRect(bounds);
 }
 
 void SetupLabelForTray(views::Label* label) {
   label->SetFont(
       label->font().DeriveFont(2, gfx::Font::BOLD));
   label->SetAutoColorReadabilityEnabled(false);
@@ skipping 32 matching lines @@
     tray_view->set_border(views::Border::CreateEmptyBorder(
         kTrayLabelItemVerticalPaddingVeriticalAlignment,
         horizontal_padding,
         kTrayLabelItemVerticalPaddingVeriticalAlignment,
         horizontal_padding));
   }
 }
 
 }  // namespace internal
 }  // namespace ash