Move const double data out of header file

components/offline_pages/offline_page_storage_manager.h

 // Copyright 2016 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 COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_STORAGE_MANAGER_H_
 #define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_STORAGE_MANAGER_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "components/offline_pages/archive_manager.h"
 #include "components/offline_pages/offline_page_types.h"
 
 namespace base {
 class Clock;
 }  // namespace base
 
 namespace offline_pages {
 
 // Maximum % of total available storage that will be occupied by offline pages
 // before a storage clearup.
-const double kOfflinePageStorageLimit = 0.3;
-// The target % of storage usage we try to reach below when expiring pages.
-const double kOfflinePageStorageClearThreshold = 0.1;
-// The time that the storage cleanup will be triggered again since the last one.
-const base::TimeDelta kClearStorageInterval = base::TimeDelta::FromMinutes(10);
-// The time that the page record will be removed from the store since the page
-// has been expired.
-const base::TimeDelta kRemovePageItemInterval = base::TimeDelta::FromDays(21);
+struct constants {
+  static constexpr double kOfflinePageStorageLimit = 0.3;
+  // The target % of storage usage we try to reach below when expiring pages.
+  static constexpr double kOfflinePageStorageClearThreshold = 0.1;
+  // The time that the storage cleanup will be triggered again since the last
+  // one.
+  static constexpr base::TimeDelta kClearStorageInterval =
+      base::TimeDelta::FromMinutes(10);
+  // The time that the page record will be removed from the store since the page
+  // has been expired.
+  static constexpr base::TimeDelta kRemovePageItemInterval =
+      base::TimeDelta::FromDays(21);
+};
 
 class ClientPolicyController;
 class OfflinePageModel;
 
 // This class is used for storage management of offline pages. It provides
 // a ClearPagesIfNeeded method which is used to clear expired offline pages
 // based on last_access_time and lifetime policy of its namespace.
 // It has its own throttle mechanism so calling the method would not be
 // guaranteed to clear the pages immediately.
 //
@@ skipping 106 matching lines @@
   std::unique_ptr<base::Clock> clock_;
 
   base::WeakPtrFactory<OfflinePageStorageManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflinePageStorageManager);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_STORAGE_MANAGER_H_