Add FakeClipboard implementation for unit tests.

ui/base/clipboard/clipboard_win.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.
 
 // Many of these functions are based on those found in
 // webkit/port/platform/PasteboardWin.cpp
 
 #include "ui/base/clipboard/clipboard_win.h"
 
 #include <shellapi.h>
@@ skipping 370 matching lines @@
 
 // ClipboardWin implementation.
 ClipboardWin::ClipboardWin() {
   if (base::MessageLoopForUI::IsCurrent())
     clipboard_owner_.reset(new base::win::MessageWindow());
 }
 
 ClipboardWin::~ClipboardWin() {
 }
 
-uint64 ClipboardWin::GetSequenceNumber(ClipboardType type) {
+uint64 ClipboardWin::GetSequenceNumber(ClipboardType type) const {
   DCHECK_EQ(type, CLIPBOARD_TYPE_COPY_PASTE);
   return ::GetClipboardSequenceNumber();
 }
 
 bool ClipboardWin::IsFormatAvailable(const Clipboard::FormatType& format,
                                      ClipboardType type) const {
   DCHECK_EQ(type, CLIPBOARD_TYPE_COPY_PASTE);
   return ::IsClipboardFormatAvailable(format.ToFormatEtc().cfFormat) != FALSE;
 }
 
@@ skipping 451 matching lines @@
   if (!clipboard_owner_)
     return NULL;
 
   if (clipboard_owner_->hwnd() == NULL)
     clipboard_owner_->Create(base::Bind(&ClipboardOwnerWndProc));
 
   return clipboard_owner_->hwnd();
 }
 
 }  // namespace ui