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

chrome/browser/ui/views/bookmarks/bookmark_bar_view_test.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 "base/bind.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/string_number_conversions.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/app/chrome_command_ids.h"
@@ skipping 1479 matching lines @@
     ASSERT_TRUE(menu != NULL);
     ASSERT_TRUE(menu->GetSubmenu()->IsShowing());
     views::MenuItemView* child_menu = menu->GetSubmenu()->GetMenuItemAt(1);
     ASSERT_TRUE(child_menu != NULL);
 
     // The context menu and child_menu can be overlapped, calculate the
     // non-intersected Rect of the child menu and click on its center to make
     // sure the click is always on the child menu.
     gfx::Rect context_rect = context_menu->GetSubmenu()->GetBoundsInScreen();
     gfx::Rect child_menu_rect = child_menu->GetBoundsInScreen();
-    gfx::Rect clickable_rect = child_menu_rect.Subtract(context_rect);
+    gfx::Rect clickable_rect = child_menu_rect;
+    clickable_rect.Subtract(context_rect);
     ASSERT_FALSE(clickable_rect.IsEmpty());
     observer_.set_task(CreateEventTask(this, &BookmarkBarViewTest17::Step4));
     MoveMouseAndPress(clickable_rect.CenterPoint(), ui_controls::RIGHT,
         ui_controls::DOWN | ui_controls::UP, base::Closure());
     // Step4 will be invoked by ContextMenuNotificationObserver.
   }
 
   void Step4() {
     // The context menu should still be showing.
     views::MenuItemView* context_menu = bb_view_->GetContextMenu();
@@ skipping 139 matching lines @@
     Done();
   }
 };
 
 #if defined(OS_WIN)
 #define MAYBE_BookmarkBarViewTest19_SiblingMenu DISABLED_SiblingMenu
 #else
 #define MAYBE_BookmarkBarViewTest19_SiblingMenu SiblingMenu
 #endif
 VIEW_TEST(BookmarkBarViewTest19, MAYBE_BookmarkBarViewTest19_SiblingMenu)