Add a mojo bridge for PersistentPrefStore.

services/preferences/public/cpp/user_prefs_impl.h

+// Copyright 2017 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 SERVICES_PREFERENCES_PUBLIC_CPP_USER_PREFS_IMPL_H_
+#define SERVICES_PREFERENCES_PUBLIC_CPP_USER_PREFS_IMPL_H_
+
+#include <string>
+#include <vector>
+
+#include "base/memory/ref_counted.h"
+#include "base/strings/string16.h"
+#include "components/user_prefs/tracked/pref_hash_filter.h"
+#include "services/preferences/public/interfaces/preferences.mojom.h"
+#include "services/preferences/public/interfaces/tracked_preference_validation_delegate.mojom.h"
+
+namespace base {
+class FilePath;
+class SingleThreadTaskRunner;
+class SequencedTaskRunner;
+}
+
+namespace prefs {
+
+// Factory functions for creating backends for user prefs. These are temporary
+// until the Prefs service provides a mojo interface for initializing user
+// prefs.
+//
+// TODO(sammc): Make these implementation details of the prefs service when it
+// exists.
+
+void CreateUserPrefs(

[tibell, 2017/03/08 03:39:54]

Both these functions, even if temporary, could use some more docs of their
non-trivial parameters. Here's my attempt:

// Create a new mojom::PersistentPrefStore impl that runs on |io_task_runner|
and listens to messages from the other end of the |request| handle. |request| is
bound on and can only be used on |connection_task_runner|.

+    const base::FilePath& pref_filename,
+    const scoped_refptr<base::SingleThreadTaskRunner>& connection_task_runner,
+    const scoped_refptr<base::SequencedTaskRunner>& io_task_runner,
+    mojom::PersistentPrefStoreConnectorRequest request);
+
+void CreateSegregatedUserPrefs(
+    const base::FilePath& unprotected_pref_filename,
+    const base::FilePath& protected_pref_filename,
+    const std::vector<PrefHashFilter::TrackedPreferenceMetadata>&
+        tracking_configuration,
+    size_t reporting_ids_count,
+    const std::string& seed,
+    const std::string& legacy_device_id,
+    const base::string16& registry_path,
+    mojom::TrackedPreferenceValidationDelegatePtr validation_delegate,
+    const base::Closure& on_reset_on_load,
+    const scoped_refptr<base::SingleThreadTaskRunner>& connection_task_runner,
+    const scoped_refptr<base::SequencedTaskRunner>& io_task_runner,
+    mojom::PersistentPrefStoreConnectorRequest request);
+
+}  // namespace prefs
+
+#endif  // SERVICES_PREFERENCES_PUBLIC_CPP_USER_PREFS_IMPL_H_