Skeleton of the overall design for the database for Pver4

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 "components/safe_browsing_db/v4_protocol_manager_util.h"
+#include "components/safe_browsing_db/v4_store.h"
+
+namespace safe_browsing {
+
+class V4Database;
+
+typedef const base::hash_map<UpdateListIdentifier,

[Nathan Parker, 2016/05/06 16:46:35]

Are the values here filename post-fixes?

[vakh (use Gerrit instead), 2016/05/06 21:27:57]

Yes.

+                             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:
+  V4DatabaseFactory() {}
+  ~V4DatabaseFactory() {}
+  V4Database* CreateV4Database(
+      const scoped_refptr<base::SequencedTaskRunner>& db_task_runner,
+      const base::FilePath& base_path,
+      ListInfoMap list_info_map);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(V4DatabaseFactory);
+};
+
+// 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(

[Nathan Parker, 2016/05/06 16:46:35]

You probably want the factory stashed as a static private member, and make a
setter-method for it.  That way, a test can inject its own factory object and
not have to pass it down through SafeBrowsingService->V4DatabaseManager-> etc.

And then the factory can be pure-virtual, with no implementation other than in
the tests.  

An example:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/saf...

[vakh (use Gerrit instead), 2016/05/06 21:27:57]

Done.

[vakh (use Gerrit instead), 2016/05/06 21:32:21]

A lot of classes under safe_browsing[_db]/ use the factory the other way (that I
had earlier) so I did that to be consistent. But I like the virtual
implementation better since there's fewer redirection when running this code in
Chromium.

+      V4DatabaseFactory* factory,
+      const scoped_refptr<base::SequencedTaskRunner>& db_task_runner,
+      const base::FilePath& base_path,
+      ListInfoMap list_info_map);
+
+  V4Database(
+     const scoped_refptr<base::SequencedTaskRunner>& db_task_runner,
+     StoreMap store_map);
+  virtual ~V4Database();
+
+  // Deletes the current database and creates a new one.
+  virtual bool ResetDatabase();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(V4Database);
+};
+
+}  // namespace safe_browsing
+
+#endif  // COMPONENTS_SAFE_BROWSING_DB_V4_DATABASE_H_