Add non-member non-mutating methods for common gfx::Rect operations.

ui/app_list/page_switcher.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/app_list/page_switcher.h"
 
 #include <algorithm>
 
 #include "third_party/skia/include/core/SkPath.h"
 #include "ui/app_list/pagination_model.h"
@@ skipping 171 matching lines @@
   gfx::Rect rect(GetContentsBounds());
 
   CalculateButtonWidthAndSpacing(rect.width());
 
   // Makes |buttons_| horizontally center and vertically fill.
   gfx::Size buttons_size(buttons_->GetPreferredSize());
   gfx::Rect buttons_bounds(rect.CenterPoint().x() - buttons_size.width() / 2,
                            rect.y(),
                            buttons_size.width(),
                            rect.height());
-  rect.Intersect(buttons_bounds);
-  buttons_->SetBoundsRect(rect);
+  buttons_->SetBoundsRect(gfx::Intersection(rect, buttons_bounds));
 }
 
 void PageSwitcher::CalculateButtonWidthAndSpacing(int contents_width) {
   const int button_count = buttons_->child_count();
   if (!button_count)
     return;
 
   contents_width -= 2 * kButtonStripPadding;
 
   int button_width = kMinButtonWidth;
@@ skipping 58 matching lines @@
     remaining = -remaining;
     progress = -progress;
   }
 
   GetButtonByIndex(buttons_, current_page)->SetSelectedRange(remaining);
   if (model_->is_valid_page(target_page))
     GetButtonByIndex(buttons_, target_page)->SetSelectedRange(progress);
 }
 
 }  // namespace app_list