Pref service: expose all read-only PrefStores through Mojo

services/preferences/public/cpp/pref_store_client.cc

Index: services/preferences/public/cpp/pref_store_client.cc
diff --git a/services/preferences/public/cpp/pref_store_client.cc b/services/preferences/public/cpp/pref_store_client.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fd6708cd679f9822def4979d6eec8615e1e797b8
--- /dev/null
+++ b/services/preferences/public/cpp/pref_store_client.cc
@@ -0,0 +1,77 @@
+// 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_store_client.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+#include "services/preferences/public/cpp/pref_store_impl.h"
+
+namespace prefs {
+
+PrefStoreClient::PrefStoreClient(mojom::PrefStoreConnectionPtr connection)
+    : cached_prefs_(std::move(connection->initial_prefs)),
+      initialized_(connection->is_initialized),
+      observer_binding_(this, std::move(connection->observer)) {}
+
+void PrefStoreClient::AddObserver(PrefStore::Observer* observer) {
+  observers_.AddObserver(observer);
+}
+
+void PrefStoreClient::RemoveObserver(PrefStore::Observer* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+bool PrefStoreClient::HasObservers() const {
+  return observers_.might_have_observers();
+}
+
+bool PrefStoreClient::IsInitializationComplete() const {
+  return initialized_;
+}
+
+bool PrefStoreClient::GetValue(const std::string& key,
+                               const base::Value** result) const {
+  DCHECK(initialized_);
+  return cached_prefs_->Get(key, result);
+}
+
+std::unique_ptr<base::DictionaryValue> PrefStoreClient::GetValues() const {
+  DCHECK(initialized_);
+  return cached_prefs_->CreateDeepCopy();
+}
+
+PrefStoreClient::~PrefStoreClient() = default;
+
+void PrefStoreClient::OnPrefChanged(const std::string& key,
+                                    std::unique_ptr<base::Value> value) {
+  bool changed = false;
+  if (!value) {  // Delete
+    if (cached_prefs_->RemovePath(key, nullptr))
+      changed = true;
+  } else {
+    const base::Value* prev;
+    if (cached_prefs_->Get(key, &prev)) {
+      if (!prev->Equals(value.get())) {
+        cached_prefs_->Set(key, std::move(value));
+        changed = true;
+      }
+    } else {
+      cached_prefs_->Set(key, std::move(value));
+      changed = true;
+    }
+  }
+  if (changed) {
+    for (Observer& observer : observers_)
+      observer.OnPrefValueChanged(key);
+  }
+}
+
+void PrefStoreClient::OnInitializationCompleted(bool succeeded) {
+  if (!initialized_) {
+    initialized_ = true;
+    for (Observer& observer : observers_)
+      observer.OnInitializationCompleted(true);
+  }
+}
+
+}  // namespace prefs