status_icons: Factor out status icon observer into its own header file.

chrome/browser/status_icons/status_icon.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_STATUS_ICONS_STATUS_ICON_H_
 #define CHROME_BROWSER_STATUS_ICONS_STATUS_ICON_H_
 #pragma once
 
+#include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/observer_list.h"
 #include "base/string16.h"
 
 class SkBitmap;
 
 namespace ui {
 class MenuModel;
 }
 
+class StatusIconObserver;
+
 class StatusIcon {
  public:
   StatusIcon();
   virtual ~StatusIcon();
 
   // Sets the image associated with this status icon.
   virtual void SetImage(const SkBitmap& image) = 0;
 
   // Sets the image associated with this status icon when pressed.
   virtual void SetPressedImage(const SkBitmap& image) = 0;
 
   // Sets the hover text for this status icon.
   virtual void SetToolTip(const string16& tool_tip) = 0;
 
   // Displays a notification balloon with the specified contents.
   // Depending on the platform it might not appear by the icon tray.
   virtual void DisplayBalloon(const SkBitmap& icon,
                               const string16& title,
                               const string16& contents) = 0;
 
   // Set the context menu for this icon. The icon takes ownership of the passed
   // context menu. Passing NULL results in no menu at all.
   void SetContextMenu(ui::MenuModel* menu);
 
-  class Observer {
-   public:
-    virtual ~Observer() {}
-
-    // Called when the user clicks on the system tray icon. Clicks that result
-    // in the context menu being displayed will not be passed to this observer
-    // (i.e. if there's a context menu set on this status icon, and the user
-    // right clicks on the icon to display the context menu, OnClicked will not
-    // be called).
-    // Note: Chrome OS displays the context menu on left button clicks.
-    // This will only be fired for this platform if no context menu is present.
-    virtual void OnClicked() = 0;
-  };
-
   // Adds/Removes an observer for clicks on the status icon. If an observer is
   // registered, then left clicks on the status icon will result in the observer
   // being called, otherwise, both left and right clicks will display the
   // context menu (if any).
-  void AddObserver(Observer* observer);
-  void RemoveObserver(Observer* observer);
+  void AddObserver(StatusIconObserver* observer);
+  void RemoveObserver(StatusIconObserver* observer);
 
   // Returns true if there are registered click observers.
-  bool HasObservers();
+  bool HasObservers() const;
 
   // Dispatches a click event to the observers.
   void DispatchClickEvent();
 
  protected:
   // Invoked after a call to SetContextMenu() to let the platform-specific
   // subclass update the native context menu based on the new model. If NULL is
   // passed, subclass should destroy the native context menu.
   virtual void UpdatePlatformContextMenu(ui::MenuModel* model) = 0;
 
  private:
-  ObserverList<Observer> observers_;
+  ObserverList<StatusIconObserver> observers_;
+
   // Context menu, if any.
   scoped_ptr<ui::MenuModel> context_menu_contents_;
+
   DISALLOW_COPY_AND_ASSIGN(StatusIcon);
 };
 
 #endif  // CHROME_BROWSER_STATUS_ICONS_STATUS_ICON_H_