Make the hcsm and its providers communicate via an observer interface.

chrome/browser/content_settings/content_settings_abstract_provider.cc

+// Copyright (c) 2011 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/content_settings/content_settings_abstract_provider.h"
+
+class ContentSettingsDetails;
+
+namespace content_settings {
+
+AbstractProvider::AbstractProvider() {
+}
+
+AbstractProvider::~AbstractProvider() {

[Bernhard Bauer, 2011/07/13 07:58:18]

Can you add a |DCHECK(observers_.empty())|?

[markusheintz_, 2011/07/13 12:48:16]

Done.

[Bernhard Bauer, 2011/07/13 13:21:28]

Actually, now that you use an |ObserverList| you can declare it as
ObservList<Foo, true> to get automatic checking ;-)

[markusheintz_, 2011/07/13 14:14:42]

Done.

+}
+
+void AbstractProvider::AddObserver(Observer* observer) {
+  observers_.insert(observer);
+}
+
+void AbstractProvider::RemoveObserver(Observer* observer) {
+  observers_.erase(observer);
+}
+
+void AbstractProvider::NotifyObservers(
+    const ContentSettingsDetails& details) const {
+  for (ObserverSet::const_iterator observer = observers_.begin();
+       observer != observers_.end();
+       ++observer) {
+    (*observer)->OnContentSettingChanged(details);
+  }
+}
+
+void AbstractProvider::RemoveAllObserver() {
+  observers_.clear();
+}
+
+}  // namespace content_settings