PreferencesManager

chrome/browser/prefs/preferences_manager.cc

+// 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.
+
+#include "chrome/browser/prefs/preferences_manager.h"
+
+#include "base/auto_reset.h"
+#include "base/bind.h"
+#include "base/values.h"
+#include "chrome/browser/profiles/profile.h"
+#include "components/prefs/pref_change_registrar.h"
+#include "components/prefs/pref_service.h"
+
+PreferencesManager::PreferencesManager(Profile* profile)
+    : preferences_change_registrar_(new PrefChangeRegistrar),
+      setting_preferences_(false) {
+  DCHECK(profile);
+  service_ = profile->GetPrefs();
+  preferences_change_registrar_->Init(service_);
+}
+
+PreferencesManager::~PreferencesManager() {}
+
+void PreferencesManager::PreferenceChanged(const std::string& preference_name) {
+  if (setting_preferences_)
+    return;
+  const PrefService::Preference* pref =
+      service_->FindPreference(preference_name);
+  base::DictionaryValue dictionary;
+  dictionary.Set(preference_name, pref->GetValue()->CreateDeepCopy());
+  client_->OnPreferencesChanged(dictionary);
+}
+
+void PreferencesManager::AddObserver(
+    prefs::mojom::PreferencesObserverPtr client) {
+  // TODO(jonross): once service_manager::Connector supports enforcing two-way
+  // binding at connection time, update PreferencesManager to use that approach.
+  // After which enforcing bind checks will not be needed (crbug.com/674140)
+  client_ = std::move(client);
+}
+
+void PreferencesManager::SetPreferences(
+    const base::DictionaryValue& preferences) {
+  DCHECK(client_.is_bound());

[dcheng, 2016/12/15 16:17:08]

This should be an if (...) with an early return.

[jonross, 2016/12/19 15:58:13]

Done.

+  DCHECK(!setting_preferences_);
+  // We ignore preference changes caused by us.
+  base::AutoReset<bool> setting_preferences(&setting_preferences_, true);
+  for (base::DictionaryValue::Iterator it(preferences); !it.IsAtEnd();
+       it.Advance()) {
+    if (!preferences_change_registrar_->IsObserved(it.key()))
+      continue;
+    const PrefService::Preference* pref = service_->FindPreference(it.key());
+    if (!pref) {
+      DLOG(ERROR) << "Preference " << it.key() << " not found.\n";
+      continue;
+    }
+    if (it.value().Equals(pref->GetValue()))
+      continue;
+    service_->Set(it.key(), it.value());
+  }
+}
+
+void PreferencesManager::Subscribe(
+    const std::vector<std::string>& preferences) {
+  DCHECK(client_.is_bound());
+  base::DictionaryValue dictionary;
+  for (auto& it : preferences) {
+    const PrefService::Preference* pref = service_->FindPreference(it);
+    if (!pref) {
+      DLOG(ERROR) << "Preference " << it << " not found.\n";
+      continue;
+    }
+    // PreferenceManager lifetime is managed by a mojo::StrongBindingPtr owned
+    // by PreferenceConnectionManager. It will outlive
+    // |preferences_change_registrar_| which it owns.
+    preferences_change_registrar_->Add(
+        it, base::Bind(&PreferencesManager::PreferenceChanged,
+                       base::Unretained(this)));
+    dictionary.Set(it, pref->GetValue()->CreateDeepCopy());
+  }
+
+  if (dictionary.empty())
+    return;
+  client_->OnPreferencesChanged(dictionary);
+}