ui: Cleanup class/struct forward declarations

ui/base/clipboard/clipboard.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_BASE_CLIPBOARD_CLIPBOARD_H_
 #define UI_BASE_CLIPBOARD_CLIPBOARD_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 11 matching lines @@
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread_checker.h"
 #include "build/build_config.h"
 #include "ui/base/clipboard/clipboard_types.h"
 #include "ui/base/ui_base_export.h"
 
 #if defined(OS_WIN)
 #include <objidl.h>
 #endif
 
-namespace base {
-class FilePath;
-
-namespace win {
-class MessageWindow;
-}  // namespace win
-}  // namespace base
-
-namespace gfx {
-class Size;
-}
-
 class SkBitmap;
 
 #ifdef __OBJC__
 @class NSString;
 #else
 class NSString;
 #endif
 
 namespace ui {
-template <typename T>
-class ClipboardTest;
 class TestClipboard;
 class ScopedClipboardWriter;
 
 class UI_BASE_EXPORT Clipboard : NON_EXPORTED_BASE(public base::ThreadChecker) {
  public:
   // MIME type constants.
   static const char kMimeTypeText[];
   static const char kMimeTypeURIList[];
   static const char kMimeTypeDownloadURL[];
   static const char kMimeTypeMozillaURL[];
@@ skipping 283 matching lines @@
 
   // Mutex that controls access to |g_clipboard_map|.
   static base::LazyInstance<base::Lock>::Leaky clipboard_map_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(Clipboard);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_CLIPBOARD_CLIPBOARD_H_