Refactor Clipboard Last Modified Time Storage

ui/base/clipboard/clipboard.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 "ui/base/clipboard/clipboard.h"
 
 #include <algorithm>
 #include <iterator>
 #include <limits>
 #include <memory>
@@ skipping 68 matching lines @@
 void Clipboard::DestroyClipboardForCurrentThread() {
   base::AutoLock lock(clipboard_map_lock_.Get());
 
   ClipboardMap* clipboard_map = clipboard_map_.Pointer();
   base::PlatformThreadId id = base::PlatformThread::CurrentId();
   ClipboardMap::iterator it = clipboard_map->find(id);
   if (it != clipboard_map->end())
     clipboard_map->erase(it);
 }
 
-base::Time Clipboard::GetClipboardLastModifiedTime() const {
+base::Time Clipboard::GetLastModifiedTime() const {
   return base::Time();
 }
 
+void Clipboard::ClearLastModifiedTime() {}
+
 void Clipboard::DispatchObject(ObjectType type, const ObjectMapParams& params) {
   // Ignore writes with empty parameters.
   for (const auto& param : params) {
     if (param.empty())
       return;
   }
 
   switch (type) {
     case CBF_TEXT:
       WriteText(&(params[0].front()), params[0].size());
@@ skipping 58 matching lines @@
       std::find(allowed_threads->begin(), allowed_threads->end(), id) ==
           allowed_threads->end()) {
     NOTREACHED();
     base::debug::DumpWithoutCrashing();
   }
 
   return id;
 }
 
 }  // namespace ui