mac: Remove code that was only needed on 10.5

chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_BROWSER_UI_COCOA_TABS_TAB_STRIP_DRAG_CONTROLLER_H_
 #define CHROME_BROWSER_UI_COCOA_TABS_TAB_STRIP_DRAG_CONTROLLER_H_
 
 #import <Cocoa/Cocoa.h>
 #include <map>
 
@@ skipping 37 matching lines @@
   TabWindowController* sourceController_;  // weak. controller starting the drag
   NSWindow* sourceWindow_;  // Weak. The window starting the drag.
   NSRect sourceWindowFrame_;
   NSRect sourceTabFrame_;
 
   TabController* draggedTab_;  // Weak. The tab controller being dragged.
 
   TabWindowController* draggedController_;  // Weak. Controller being dragged.
   NSWindow* dragWindow_;  // Weak. The window being dragged
   NSWindow* dragOverlay_;  // Weak. The overlay being dragged
-  // Cache workspace IDs per-drag because computing them on 10.5 with
-  // CGWindowListCreateDescriptionFromArray is expensive.
-  // resetDragControllers clears this cache.
-  //
-  // TODO(davidben): When 10.5 becomes unsupported, remove this.
-  std::map<CGWindowID, int> workspaceIDCache_;
 
   TabWindowController* targetController_;  // weak. Controller being targeted
 }
 
 // Designated initializer.
 - (id)initWithTabStripController:(TabStripController*)controller;
 
 // TabDraggingEventTarget methods are also implemented.
 
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_TABS_TAB_STRIP_DRAG_CONTROLLER_H_