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

chrome/browser/content_settings/content_settings_mock_observer.h

+// 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.
+
+#ifndef CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_MOCK_OBSERVER_H_
+#define CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_MOCK_OBSERVER_H_
+
+#include <string>
+
+#include "chrome/browser/content_settings/content_settings_observer.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace content_settings {
+
+class MockObserver : public Observer {
+ public:
+  MockObserver() { }
+  virtual ~MockObserver()  {}
+
+  MOCK_METHOD4(OnContentSettingChanged,
+               void(ContentSettingsPattern primary_pattern,
+                    ContentSettingsPattern secondary_pattern,
+                    ContentSettingsType content_type,
+                    std::string resource_identifier));
+};
+}  // content_settings
+
+#endif  // CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_MOCK_OBSERVER_H_