[Offline pages] Adding ArchiveManager to abstract offline archives management

components/offline_pages/offline_page_storage_manager_unittest.cc

Index: components/offline_pages/offline_page_storage_manager_unittest.cc
diff --git a/components/offline_pages/offline_page_storage_manager_unittest.cc b/components/offline_pages/offline_page_storage_manager_unittest.cc
index 3f4890c4bf8f88b5068e89571b094a4ea998f3ff..65c2bc60cfc22af190529750882fdb9ca6836770 100644
--- a/components/offline_pages/offline_page_storage_manager_unittest.cc
+++ b/components/offline_pages/offline_page_storage_manager_unittest.cc
@@ -50,6 +50,8 @@ class StorageManagerTestClient : public OfflinePageStorageManager::Client {
       AddPages(setting);
   }
 
+  ~StorageManagerTestClient() override;
+
   void GetAllPages(const MultipleOfflinePageItemCallback& callback) override {
     callback.Run(pages_);
   }
@@ -79,6 +81,8 @@ class StorageManagerTestClient : public OfflinePageStorageManager::Client {
   int64_t next_offline_id_;
 };
 
+StorageManagerTestClient::~StorageManagerTestClient() {}
+
 void StorageManagerTestClient::AddPages(const PageSettings& setting) {
   std::string name_space = setting.name_space;
   int fresh_pages_count = setting.fresh_pages_count;