Pref service: expose all read-only PrefStores through Mojo

services/preferences/public/cpp/pref_store_manager_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_PREF_STORE_MANAGER_IMPL_H_
+#define SERVICES_PREFERENCES_PUBLIC_CPP_PREF_STORE_MANAGER_IMPL_H_
+
+#include "base/compiler_specific.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "components/prefs/pref_value_store.h"
+#include "mojo/public/cpp/bindings/binding_set.h"
+#include "services/preferences/public/interfaces/preferences.mojom.h"
+#include "services/service_manager/public/cpp/interface_factory.h"
+#include "services/service_manager/public/cpp/service.h"
+
+namespace prefs {
+
+// This class mediates the connection of clients who wants to read preferences
+// and the pref stores that store those preferences. Pref stores use the
+// |PrefStoreRegistry| interface to register themselves with the manager and
+// clients use the |PrefStoreConnector| interface to connect to these stores.
+class PrefStoreManagerImpl
+    : public NON_EXPORTED_BASE(mojom::PrefStoreRegistry),
+      public NON_EXPORTED_BASE(mojom::PrefStoreConnector),
+      public NON_EXPORTED_BASE(
+          service_manager::InterfaceFactory<mojom::PrefStoreConnector>),
+      public NON_EXPORTED_BASE(
+          service_manager::InterfaceFactory<mojom::PrefStoreRegistry>),
+      public NON_EXPORTED_BASE(service_manager::Service) {
+ public:
+  using PrefStoreTypes = std::set<PrefValueStore::PrefStoreType>;
+
+  // Only replies to Connect calls when all |expected_pref_stores| have
+  // registered.
+  PrefStoreManagerImpl(PrefStoreTypes expected_pref_stores);
+  ~PrefStoreManagerImpl() override;
+
+  // PrefStores used by Chrome by default.
+  static PrefStoreTypes DefaultStores();
+
+ private:
+  // mojom::PrefStoreRegistry:
+  void Register(mojom::PrefStorePtr pref_store_ptr,
+                PrefValueStore::PrefStoreType) override;
+
+  // mojom::PrefStoreConnector:
+  void Connect(const ConnectCallback& callback) override;
+
+  // service_manager::InterfaceFactory<PrefStoreConnector>:
+  void Create(const service_manager::Identity& remote_identity,
+              prefs::mojom::PrefStoreConnectorRequest request) override;
+
+  // service_manager::InterfaceFactory<PrefStoreRegistry>:
+  void Create(const service_manager::Identity& remote_identity,
+              prefs::mojom::PrefStoreRegistryRequest request) override;
+
+  // service_manager::Service:
+  void OnStart() override;
+  bool OnConnect(const service_manager::ServiceInfo& remote_info,
+                 service_manager::InterfaceRegistry* registry) override;
+
+  // Have all the expected PrefStores connected?
+  bool AllConnected() const;
+
+  // Used to make sure all pref stores have been registered before replying to
+  // any Connect calls.
+  class ConnectionBarrier;
+
+  // PrefStores that need to register before replying to any Connect calls.
+  PrefStoreTypes expected_pref_stores_;
+
+  using PrefStorePtrs =
+      std::unordered_map<PrefValueStore::PrefStoreType, mojom::PrefStorePtr>;
+
+  // Registered pref stores.
+  PrefStorePtrs pref_store_ptrs_;
+
+  mojo::BindingSet<mojom::PrefStoreConnector> connector_bindings_;
+  mojo::BindingSet<mojom::PrefStoreRegistry> registry_bindings_;
+
+  // We hold on to the connection request callbacks until all expected
+  // PrefStores have registered.
+  std::vector<ConnectCallback> pending_callbacks_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrefStoreManagerImpl);
+};
+
+}  // namespace prefs
+
+#endif  // SERVICES_PREFERENCES_PUBLIC_CPP_PREF_STORE_MANAGER_IMPL_H_