gtk: Some code cleanup for the message-pump.

base/message_loop/message_pump_gtk.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 BASE_MESSAGE_LOOP_MESSAGE_PUMP_GTK_H_
 #define BASE_MESSAGE_LOOP_MESSAGE_PUMP_GTK_H_
 
 #include "base/message_loop/message_pump_glib.h"
 
 typedef union _GdkEvent GdkEvent;
 typedef struct _XDisplay Display;
 
 namespace base {
 
 // The documentation for this class is in message_pump_glib.h
-class MessagePumpObserver {
+class MessagePumpGdkObserver {
  public:
   // This method is called before processing a message.
   virtual void WillProcessEvent(GdkEvent* event) = 0;
 
   // This method is called after processing a message.
   virtual void DidProcessEvent(GdkEvent* event) = 0;
 
  protected:
-  virtual ~MessagePumpObserver() {}
-};
-
-// The documentation for this class is in message_pump_glib.h
-//
-// The nested loop is exited by either posting a quit, or returning false
-// from Dispatch.
-class MessagePumpDispatcher {
- public:
-  // Dispatches the event. If true is returned processing continues as
-  // normal. If false is returned, the nested loop exits immediately.
-  virtual bool Dispatch(GdkEvent* event) = 0;
-
- protected:
-  virtual ~MessagePumpDispatcher() {}
+  virtual ~MessagePumpGdkObserver() {}
 };
 
 // This class implements a message-pump for dispatching GTK events.
 class BASE_EXPORT MessagePumpGtk : public MessagePumpGlib {
  public:
   MessagePumpGtk();
   virtual ~MessagePumpGtk();
 
   // Dispatch an available GdkEvent. Essentially this allows a subclass to do
   // some task before/after calling the default handler (EventDispatcher).
   void DispatchEvents(GdkEvent* event);
 
   // Returns default X Display.
   static Display* GetDefaultXDisplay();
 
+  // Adds an Observer, which will start receiving notifications immediately.
+  void AddObserver(MessagePumpGdkObserver* observer);
+
+  // Removes an Observer.  It is safe to call this method while an Observer is
+  // receiving a notification callback.
+  void RemoveObserver(MessagePumpGdkObserver* observer);
+
  private:
   // Invoked from EventDispatcher. Notifies all observers we're about to
   // process an event.
   void WillProcessEvent(GdkEvent* event);
 
   // Invoked from EventDispatcher. Notifies all observers we processed an
   // event.
   void DidProcessEvent(GdkEvent* event);
 
   // Callback prior to gdk dispatching an event.
   static void EventDispatcher(GdkEvent* event, void* data);
 
+  // List of observers.
+  ObserverList<MessagePumpGdkObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(MessagePumpGtk);
 };
 
 typedef MessagePumpGtk MessagePumpForUI;
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_GTK_H_