Clean up pref change notification handling.

chrome/browser/prefs/pref_notifier_impl.cc

Index: chrome/browser/prefs/pref_notifier_impl.cc
diff --git a/chrome/browser/prefs/pref_notifier_impl.cc b/chrome/browser/prefs/pref_notifier_impl.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d15f425c5ae15253e6614710f0de4cfab4e9cbfa
--- /dev/null
+++ b/chrome/browser/prefs/pref_notifier_impl.cc
@@ -0,0 +1,105 @@
+// Copyright (c) 2010 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/pref_notifier_impl.h"
+
+#include "base/stl_util-inl.h"
+#include "chrome/browser/prefs/pref_service.h"
+#include "chrome/common/notification_observer.h"
+#include "chrome/common/notification_service.h"
+
+PrefNotifierImpl::PrefNotifierImpl(PrefService* service)
+    : pref_service_(service) {
+}
+
+PrefNotifierImpl::~PrefNotifierImpl() {
+  DCHECK(CalledOnValidThread());
+
+  // Verify that there are no pref observers when we shut down.
+  for (PrefObserverMap::iterator it = pref_observers_.begin();
+       it != pref_observers_.end(); ++it) {
+    NotificationObserverList::Iterator obs_iterator(*(it->second));
+    if (obs_iterator.GetNext()) {
+      LOG(WARNING) << "pref observer found at shutdown " << it->first;
+    }
+  }
+
+  STLDeleteContainerPairSecondPointers(pref_observers_.begin(),
+                                       pref_observers_.end());
+  pref_observers_.clear();
+}
+
+void PrefNotifierImpl::AddPrefObserver(const char* path,
+                                       NotificationObserver* obs) {
+  // Get the pref observer list associated with the path.
+  NotificationObserverList* observer_list = NULL;
+  const PrefObserverMap::iterator observer_iterator =
+      pref_observers_.find(path);
+  if (observer_iterator == pref_observers_.end()) {
+    observer_list = new NotificationObserverList;
+    pref_observers_[path] = observer_list;
+  } else {
+    observer_list = observer_iterator->second;
+  }
+
+  // Verify that this observer doesn't already exist.
+  NotificationObserverList::Iterator it(*observer_list);
+  NotificationObserver* existing_obs;
+  while ((existing_obs = it.GetNext()) != NULL) {
+    DCHECK(existing_obs != obs) << path << " observer already registered";
+    if (existing_obs == obs)
+      return;
+  }
+
+  // Ok, safe to add the pref observer.
+  observer_list->AddObserver(obs);
+}
+
+void PrefNotifierImpl::RemovePrefObserver(const char* path,
+                                          NotificationObserver* obs) {
+  DCHECK(CalledOnValidThread());
+
+  const PrefObserverMap::iterator observer_iterator =
+      pref_observers_.find(path);
+  if (observer_iterator == pref_observers_.end()) {
+    return;
+  }
+
+  NotificationObserverList* observer_list = observer_iterator->second;
+  observer_list->RemoveObserver(obs);
+}
+
+void PrefNotifierImpl::OnPreferenceChanged(const std::string& path) {
+  FireObservers(path);
+}
+
+void PrefNotifierImpl::OnInitializationCompleted() {
+  DCHECK(CalledOnValidThread());
+
+  NotificationService::current()->Notify(
+      NotificationType::PREF_INITIALIZATION_COMPLETED,
+      Source<PrefService>(pref_service_),
+      NotificationService::NoDetails());
+}
+
+void PrefNotifierImpl::FireObservers(const std::string& path) {
+  DCHECK(CalledOnValidThread());
+
+  // Only send notifications for registered preferences.
+  if (!pref_service_->FindPreference(path.c_str()))
+    return;
+
+  const PrefObserverMap::iterator observer_iterator =
+      pref_observers_.find(path);
+  if (observer_iterator == pref_observers_.end())
+    return;
+
+  NotificationObserverList::Iterator it(*(observer_iterator->second));
+  NotificationObserver* observer;
+  while ((observer = it.GetNext()) != NULL) {
+    observer->Observe(NotificationType::PREF_CHANGED,
+                      Source<PrefService>(pref_service_),
+                      Details<const std::string>(&path));
+  }
+}