mac: Delete GetCachedImageWithName(), it's no longer used.

ui/gfx/mac/nsimage_cache.h

-// 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.
-
-#ifndef UI_GFX_MAC_NSIMAGE_CACHE_H_
-#define UI_GFX_MAC_NSIMAGE_CACHE_H_
-
-#include "ui/base/ui_export.h"
-
-#ifdef __OBJC__
-@class NSImage;
-@class NSString;
-#else
-class NSImage;
-class NSString;
-#endif
-
-namespace gfx {
-
-// Returns an autoreleased image from the framework bundle
-// (base::mac::FrameworkBundle()) with the given name, and keeps it in memory so
-// future fetches are fast.
-// NOTE:
-//   - This should only be called on the main thread.
-//   - The caller should retain the image if they want to keep it around, as
-//     the cache could have limit on size/lifetime, etc.
-UI_EXPORT NSImage* GetCachedImageWithName(NSString* name);
-
-// Clears the image cache.
-UI_EXPORT void ClearCachedImages(void);
-
-}  // namespace gfx
-
-#endif  // UI_GFX_MAC_NSIMAGE_CACHE_H_