Make TabRestoreService::Entry noncopyable and fix up surrounding code.

components/sessions/content/content_platform_specific_tab_data.cc

 // Copyright 2015 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 "components/sessions/content/content_platform_specific_tab_data.h"
 
 #include "base/memory/ptr_util.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/web_contents.h"
 
 namespace sessions {
 
 ContentPlatformSpecificTabData::ContentPlatformSpecificTabData(
     content::WebContents* web_contents)
     :  // TODO(ajwong): This does not correctly handle storage for isolated
        // apps.
       session_storage_namespace_(web_contents->GetController()
                                      .GetDefaultSessionStorageNamespace()) {}
 
 ContentPlatformSpecificTabData::ContentPlatformSpecificTabData() {}
 
 ContentPlatformSpecificTabData::~ContentPlatformSpecificTabData() {}
 
-std::unique_ptr<PlatformSpecificTabData>
-ContentPlatformSpecificTabData::Clone() {
-  ContentPlatformSpecificTabData* clone = new ContentPlatformSpecificTabData();
-  clone->session_storage_namespace_ = session_storage_namespace_;
-  return base::WrapUnique(clone);
-}
-
 }  // namespace sessions