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

ash/wm/base_layout_manager.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/wm/base_layout_manager.h"
 
 #include "ash/screen_ash.h"
 #include "ash/shell.h"
 #include "ash/wm/shelf_layout_manager.h"
 #include "ash/wm/window_animations.h"
@@ skipping 206 matching lines @@
       SetChildBoundsDirect(
           window, ScreenAsh::GetMaximizedWindowBoundsInParent(window));
     } else if (wm::IsWindowFullscreen(window)) {
       SetChildBoundsDirect(
           window, ScreenAsh::GetDisplayBoundsInParent(window));
     } else {
       // The work area may be smaller than the full screen.
       gfx::Rect display_rect =
           ScreenAsh::GetDisplayWorkAreaBoundsInParent(window);
       // Put as much of the window as possible within the display area.
-      window->SetBounds(window->bounds().AdjustToFit(display_rect));
+      gfx::Rect bounds = window->bounds();
+      bounds.AdjustToFit(display_rect);
+      window->SetBounds(bounds);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace ash