Pref service: add a factory to create the client lib

services/preferences/public/cpp/pref_service_factory.cc

+// 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.
+
+#include "services/preferences/public/cpp/pref_service_factory.h"
+
+#include "base/callback_helpers.h"
+#include "components/prefs/persistent_pref_store.h"
+#include "components/prefs/pref_notifier_impl.h"
+#include "components/prefs/pref_registry.h"
+#include "components/prefs/pref_service.h"
+#include "components/prefs/pref_value_store.h"
+#include "services/preferences/public/cpp/persistent_pref_store_client.h"
+#include "services/preferences/public/cpp/pref_store_client.h"
+#include "services/preferences/public/interfaces/preferences.mojom.h"
+#include "services/service_manager/public/cpp/connector.h"
+
+namespace prefs {
+namespace {
+
+// Used to implement a "fire and forget" pattern where we call an interface
+// method, with an attached error handler, but don't care to hold on to the
+// InterfacePtr after.
+template <typename Interface>
+class RefCountedInterfacePtr
+    : public base::RefCounted<RefCountedInterfacePtr<Interface>> {
+ public:
+  mojo::InterfacePtr<Interface>& get() { return ptr_; }
+  void reset() { ptr_.reset(); }
+
+ private:
+  friend class base::RefCounted<RefCountedInterfacePtr<Interface>>;
+  ~RefCountedInterfacePtr() = default;
+
+  mojo::InterfacePtr<Interface> ptr_;
+};
+
+void DoNothingHandleReadError(PersistentPrefStore::PrefReadError error) {}
+
+class ConnectionBarrier : public base::RefCounted<ConnectionBarrier> {
+ public:
+  static void Create(service_manager::Connector* connector,
+                     scoped_refptr<PrefRegistry> pref_registry,
+                     ConnectCallback callback);
+
+ private:
+  friend class base::RefCounted<ConnectionBarrier>;
+  ConnectionBarrier(scoped_refptr<PrefRegistry> pref_registry,
+                    scoped_refptr<PersistentPrefStore> persistent_pref_store,
+                    ConnectCallback callback);
+  ~ConnectionBarrier() = default;
+
+  void OnConnect(
+      scoped_refptr<RefCountedInterfacePtr<mojom::PrefStoreConnector>> unused,
+      scoped_refptr<PrefRegistry> pref_registry,
+      std::unordered_map<PrefValueStore::PrefStoreType,
+                         mojom::PrefStoreConnectionPtr> connections);
+
+  void OnConnectError(
+      scoped_refptr<RefCountedInterfacePtr<mojom::PrefStoreConnector>> unused);
+
+  scoped_refptr<PrefRegistry> pref_registry_;
+  scoped_refptr<PersistentPrefStore> persistent_pref_store_;
+  ConnectCallback callback_;
+};
+
+scoped_refptr<PrefStore> CreatePrefStore(
+    PrefValueStore::PrefStoreType store_type,
+    std::unordered_map<PrefValueStore::PrefStoreType,
+                       mojom::PrefStoreConnectionPtr>* connections) {
+  auto pref_store_it = connections->find(store_type);
+  if (pref_store_it != connections->end()) {
+    return make_scoped_refptr(
+        new PrefStoreClient(std::move(pref_store_it->second)));
+  } else {
+    return nullptr;
+  }
+}
+
+ConnectionBarrier::ConnectionBarrier(
+    scoped_refptr<PrefRegistry> pref_registry,
+    scoped_refptr<PersistentPrefStore> persistent_pref_store,
+    ConnectCallback callback)
+    : pref_registry_(std::move(pref_registry)),
+      persistent_pref_store_(std::move(persistent_pref_store)),
+      callback_(std::move(callback)) {}
+
+void ConnectionBarrier::OnConnect(
+    scoped_refptr<RefCountedInterfacePtr<mojom::PrefStoreConnector>>
+        connector_ptr,
+    scoped_refptr<PrefRegistry> pref_registry,
+    std::unordered_map<PrefValueStore::PrefStoreType,
+                       mojom::PrefStoreConnectionPtr> connections) {
+  scoped_refptr<PrefStore> managed_prefs =
+      CreatePrefStore(PrefValueStore::MANAGED_STORE, &connections);
+  scoped_refptr<PrefStore> supervised_user_prefs =
+      CreatePrefStore(PrefValueStore::SUPERVISED_USER_STORE, &connections);
+  scoped_refptr<PrefStore> extension_prefs =
+      CreatePrefStore(PrefValueStore::EXTENSION_STORE, &connections);
+  scoped_refptr<PrefStore> command_line_prefs =
+      CreatePrefStore(PrefValueStore::COMMAND_LINE_STORE, &connections);
+  scoped_refptr<PrefStore> recommended_prefs =
+      CreatePrefStore(PrefValueStore::RECOMMENDED_STORE, &connections);
+  scoped_refptr<PrefStore> default_prefs =
+      CreatePrefStore(PrefValueStore::DEFAULT_STORE, &connections);
+  PrefNotifierImpl* pref_notifier = new PrefNotifierImpl();
+  auto* pref_value_store = new PrefValueStore(
+      managed_prefs.get(), supervised_user_prefs.get(), extension_prefs.get(),
+      command_line_prefs.get(), persistent_pref_store_.get(),
+      recommended_prefs.get(), default_prefs.get(), pref_notifier);
+  base::ResetAndReturn(&callback_)
+      .Run(base::MakeUnique<::PrefService>(
+          pref_notifier, pref_value_store, persistent_pref_store_.get(),
+          pref_registry_.get(), base::Bind(&DoNothingHandleReadError), true));
+  connector_ptr->reset();
+}
+
+void ConnectionBarrier::OnConnectError(
+    scoped_refptr<RefCountedInterfacePtr<mojom::PrefStoreConnector>>
+        connector_ptr) {
+  callback_.Run(nullptr);
+  connector_ptr->reset();
+}
+
+// static
+void ConnectionBarrier::Create(service_manager::Connector* connector,
+                               scoped_refptr<PrefRegistry> pref_registry,
+                               ConnectCallback callback) {
+  // Connect to user pref store.
+  mojom::PersistentPrefStoreConnectorPtr persistent_connector_ptr;
+  connector->BindInterface(mojom::kPrefStoreServiceName,
+                           &persistent_connector_ptr);
+  auto barrier = make_scoped_refptr(new ConnectionBarrier(
+      std::move(pref_registry),
+      make_scoped_refptr(
+          new PersistentPrefStoreClient(std::move(persistent_connector_ptr))),
+      std::move(callback)));
+
+  // Connect to all other pref stores.
+  auto connector_ptr = make_scoped_refptr(
+      new RefCountedInterfacePtr<mojom::PrefStoreConnector>());
+  connector->BindInterface(mojom::kPrefStoreServiceName, &connector_ptr->get());
+  connector_ptr->get().set_connection_error_handler(
+      base::Bind(&ConnectionBarrier::OnConnectError, barrier, connector_ptr));
+  connector_ptr->get()->Connect(base::Bind(&ConnectionBarrier::OnConnect,
+                                           barrier, connector_ptr,
+                                           std::move(pref_registry)));
+}
+
+}  // namespace
+
+void ConnectToPrefService(service_manager::Connector* connector,
+                          scoped_refptr<PrefRegistry> pref_registry,
+                          const ConnectCallback& callback) {
+  ConnectionBarrier::Create(connector, std::move(pref_registry), callback);
+}
+
+}  // namespace prefs