Reland: Initialize and reset V4LocalDBManager. Instantiate V4Stores.

components/safe_browsing_db/v4_database.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_SAFE_BROWSING_DB_V4_DATABASE_H_
 #define COMPONENTS_SAFE_BROWSING_DB_V4_DATABASE_H_
 
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequenced_task_runner.h"
+#include "base/single_thread_task_runner.h"
 #include "components/safe_browsing_db/v4_protocol_manager_util.h"
 #include "components/safe_browsing_db/v4_store.h"
 
 namespace safe_browsing {
 
 class V4Database;
 
+typedef base::Callback<void(std::unique_ptr<V4Database>)>
+    NewDatabaseReadyCallback;
+
 typedef const base::hash_map<UpdateListIdentifier,
                              const base::FilePath::CharType>
     ListInfoMap;
 
 typedef std::unique_ptr<
     base::hash_map<UpdateListIdentifier, std::unique_ptr<V4Store>>>
     StoreMap;
 
 // Factory for creating V4Database. Tests implement this factory to create fake
 // databases for testing.
 class V4DatabaseFactory {
  public:
   virtual ~V4DatabaseFactory() {}
   virtual V4Database* CreateV4Database(
       const scoped_refptr<base::SequencedTaskRunner>& db_task_runner,
       const base::FilePath& base_path,
       ListInfoMap list_info_map) = 0;
 };
 
 // The on-disk databases are shared among all profiles, as it doesn't contain
 // user-specific data. This object is not thread-safe, i.e. all its methods
 // should be used on the same thread that it was created on, unless specified
 // otherwise.
 // The hash-prefixes of each type are managed by a V4Store (including saving to
 // and reading from disk).
 // The V4Database serves as a single place to manage all the V4Stores.
 class V4Database {
  public:
-  // Factory method for obtaining a V4Database implementation.
-  // It is not thread safe.
-  // The availability of each list is controlled by the one flag on this
-  // method.
-  static V4Database* Create(
+  // Factory method to create a V4Database. It creates the database on the
+  // provided |db_task_runner|. When the database creation is complete, it calls
+  // the NewDatabaseReadyCallback on the same thread as it was called.
+  static void Create(
       const scoped_refptr<base::SequencedTaskRunner>& db_task_runner,
       const base::FilePath& base_path,
-      ListInfoMap list_info_map);
+      ListInfoMap list_info_map,
+      NewDatabaseReadyCallback callback);
 
-  V4Database(
-     const scoped_refptr<base::SequencedTaskRunner>& db_task_runner,
-     StoreMap store_map);
+  // Destroys the provided v4_database on its task_runner since this may be a
+  // long operation.
+  static void Destroy(std::unique_ptr<V4Database> v4_database);
+
   virtual ~V4Database();
 
   // Deletes the current database and creates a new one.
   virtual bool ResetDatabase();
 
   // Makes the passed |factory| the factory used to instantiate
   // a V4Database. Only for tests.
   static void RegisterFactoryForTest(V4DatabaseFactory* factory) {
     factory_ = factory;
   }
 
+ protected:
+  V4Database(const scoped_refptr<base::SequencedTaskRunner>& db_task_runner,
+             StoreMap store_map);
+
  private:
+  // Factory method to create a V4Database. When the database creation is
+  // complete, it calls the NewDatabaseReadyCallback on |callback_task_runner|.
+  static void CreateOnTaskRunner(
+      const scoped_refptr<base::SequencedTaskRunner>& db_task_runner,
+      const base::FilePath& base_path,
+      ListInfoMap list_info_map,
+      const scoped_refptr<base::SingleThreadTaskRunner>& callback_task_runner,
+      NewDatabaseReadyCallback callback);
+
+  const scoped_refptr<base::SequencedTaskRunner> db_task_runner_;
+
+  // Map of UpdateListIdentifier to the V4Store.
+  StoreMap store_map_;
+
   // The factory that controls the creation of V4Database objects.
   // This is used *only* by tests.
   static V4DatabaseFactory* factory_;
 
   DISALLOW_COPY_AND_ASSIGN(V4Database);
 };
 
 }  // namespace safe_browsing
 
 #endif  // COMPONENTS_SAFE_BROWSING_DB_V4_DATABASE_H_