Replace chrome::NOTIFICATION_EXTENSION_WARNING_CHANGED message with observer pattern

chrome/browser/extensions/extension_warning_set.h

 // Copyright (c) 2012 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_EXTENSIONS_EXTENSION_WARNING_SET_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_WARNING_SET_H_
 
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/memory/linked_ptr.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/observer_list.h"
 #include "base/string16.h"
 #include "base/threading/non_thread_safe.h"
 #include "googleurl/src/gurl.h"
 
 class ExtensionGlobalErrorBadge;
 class ExtensionService;
 class Profile;
 
 // TODO(battre) Remove the Extension prefix.
 
@@ skipping 104 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionWarningSet);
 };
 
 // Manages a set of warnings caused by extensions. These warnings (e.g.
 // conflicting modifications of network requests by extensions, slow extensions,
 // etc.) trigger a warning badge in the UI and and provide means to resolve
 // them. This class must be used on the UI thread only.
 class ExtensionWarningService : public base::NonThreadSafe {
  public:
+  class Observer {
+   public:
+    virtual void ExtensionWarningsChanged() = 0;
+  };
+
   // |profile| may be NULL for testing. In this case, be sure to not insert
   // any warnings.
   explicit ExtensionWarningService(Profile* profile);
   virtual ~ExtensionWarningService();
 
   // Clears all warnings of types contained in |types| and triggers a
   // chrome::NOTIFICATION_EXTENSION_WARNING message if such warnings existed.
   // If no warning remains that is not suppressed, this may deactivate a
   // warning badge on the wrench mennu.
   void ClearWarnings(const std::set<ExtensionWarning::WarningType>& types);
@@ skipping 19 matching lines @@
   // If the warning is new and has not been suppressed, this may activate a
   // badge on the wrench menu.
   void AddWarnings(scoped_ptr<ExtensionWarningSet> warnings);
 
   // Notifies the ExtensionWarningService of profile |profile_id| that new
   // |warnings| occurred and triggers a warning badge.
   static void NotifyWarningsOnUI(
       void* profile_id,
       scoped_ptr<ExtensionWarningSet> warnings);
 
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
  protected:
   // Virtual for testing.
   virtual void NotifyWarningsChanged();
 
  private:
   typedef std::set<linked_ptr<ExtensionWarning> >::const_iterator
       const_iterator;
   typedef std::set<linked_ptr<ExtensionWarning> >::iterator iterator;
 
   // Shows or hides the warning badge on the wrench menu depending on whether
   // any non-suppressed warnings exist.
   void UpdateWarningBadge();
 
   // Currently existing warnings.
   std::set<linked_ptr<ExtensionWarning> > warnings_;
 
   // Warnings that do not trigger a badge on the wrench menu.
   std::set<linked_ptr<ExtensionWarning> > badge_suppressions_;
 
   Profile* profile_;
+
+  ObserverList<Observer> observer_list_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_WARNING_SET_H_