Splits the OfflinePageModel into and interface and and implementation class.

chrome/browser/android/offline_pages/test_offline_page_model_builder.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 "chrome/browser/android/offline_pages/test_offline_page_model_builder.h"
 
 #include <utility>
 
 #include "base/memory/ref_counted.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chrome/common/chrome_constants.h"
-#include "components/offline_pages/offline_page_model.h"
+#include "components/offline_pages/offline_page_model_impl.h"
 #include "components/offline_pages/offline_page_test_store.h"
 #include "content/public/browser/browser_context.h"
 
 namespace offline_pages {
 
 std::unique_ptr<KeyedService> BuildTestOfflinePageModel(
     content::BrowserContext* context) {
   scoped_refptr<base::SingleThreadTaskRunner> task_runner =
       base::ThreadTaskRunnerHandle::Get();
 
   std::unique_ptr<OfflinePageTestStore> metadata_store(
       new OfflinePageTestStore(task_runner));
 
   base::FilePath archives_dir =
       context->GetPath().Append(chrome::kOfflinePageArchviesDirname);
 
-  return std::unique_ptr<KeyedService>(new OfflinePageModel(
+  return std::unique_ptr<KeyedService>(new OfflinePageModelImpl(
       std::move(metadata_store), archives_dir, task_runner));
 }
 
 }  // namespace offline_pages