Refactor the glib message-pump, and use it as the base for a gtk message pump and an X message pump.

base/message_pump_glib.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 BASE_MESSAGE_PUMP_GLIB_H_
 #define BASE_MESSAGE_PUMP_GLIB_H_
 #pragma once
 
 #include "base/memory/scoped_ptr.h"
 #include "base/message_pump.h"
 #include "base/observer_list.h"
 #include "base/time.h"
 
-typedef union _GdkEvent GdkEvent;
 typedef struct _GMainContext GMainContext;
 typedef struct _GPollFD GPollFD;
 typedef struct _GSource GSource;
 
 namespace base {
 
-// This class implements a MessagePump needed for TYPE_UI MessageLoops on
-// OS_LINUX platforms using GLib.
-class MessagePumpForUI : public MessagePump {
+// MessagePumpObserver is notified prior to an event being dispatched. As
+// Observers are notified of every change, they have to be FAST! The platform
+// specific implementation of the class is in message_pump_gtk/message_pump_x.
+class MessagePumpObserver;
+
+// MessagePumpDispatcher is used during a nested invocation of Run to dispatch
+// events. If Run is invoked with a non-NULL MessagePumpDispatcher, MessageLoop
+// does not dispatch events (or invoke gtk_main_do_event), rather every event is
+// passed to Dispatcher's Dispatch method for dispatch. It is up to the
+// Dispatcher to dispatch, or not, the event. The platform specific
+// implementation of the class is in message_pump_gtk/message_pump_x.
+class MessagePumpDispatcher;
+
+// This class implements a base MessagePump needed for TYPE_UI MessageLoops on
+// platforms using GLib.
+class MessagePumpGlib : public MessagePump {
  public:
-  // Observer is notified prior to a GdkEvent event being dispatched. As
-  // Observers are notified of every change, they have to be FAST!
-  class Observer {
-   public:
-    virtual ~Observer() {}
+  MessagePumpGlib();
+  virtual ~MessagePumpGlib();
 
-    // 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;
-  };
-
-  // Dispatcher is used during a nested invocation of Run to dispatch events.
-  // If Run is invoked with a non-NULL Dispatcher, MessageLoop does not
-  // dispatch events (or invoke gtk_main_do_event), rather every event is
-  // passed to Dispatcher's Dispatch method for dispatch. It is up to the
-  // Dispatcher to dispatch, or not, the event.
-  //
-  // The nested loop is exited by either posting a quit, or returning false
-  // from Dispatch.
-  class Dispatcher {
-   public:
-    virtual ~Dispatcher() {}
-    // 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;
-  };
-
-  MessagePumpForUI();
-  virtual ~MessagePumpForUI();
-
-  // Like MessagePump::Run, but GdkEvent objects are routed through dispatcher.
-  virtual void RunWithDispatcher(Delegate* delegate, Dispatcher* dispatcher);
+  // Like MessagePump::Run, but events are routed through dispatcher.
+  virtual void RunWithDispatcher(Delegate* delegate,
+                                 MessagePumpDispatcher* dispatcher);
 
   // Run a single iteration of the mainloop. A return value of true indicates
   // that an event was handled. |block| indicates if it should wait if no event
   // is ready for processing.
-  virtual bool RunOnce(GMainContext* context, bool block);
+  virtual bool RunOnce(GMainContext* context, bool block) = 0;
 
   // Internal methods used for processing the pump callbacks.  They are
   // public for simplicity but should not be used directly.  HandlePrepare
   // is called during the prepare step of glib, and returns a timeout that
   // will be passed to the poll. HandleCheck is called after the poll
   // has completed, and returns whether or not HandleDispatch should be called.
   // HandleDispatch is called if HandleCheck returned true.
   int HandlePrepare();
   bool HandleCheck();
   void HandleDispatch();
 
   // Adds an Observer, which will start receiving notifications immediately.
-  void AddObserver(Observer* observer);
+  void AddObserver(MessagePumpObserver* observer);
 
   // Removes an Observer.  It is safe to call this method while an Observer is
   // receiving a notification callback.
-  void RemoveObserver(Observer* observer);
-
-  // Dispatch an available GdkEvent. Essentially this allows a subclass to do
-  // some task before/after calling the default handler (EventDispatcher).
-  virtual void DispatchEvents(GdkEvent* event);
+  void RemoveObserver(MessagePumpObserver* observer);
 
   // Overridden from MessagePump:
   virtual void Run(Delegate* delegate);
   virtual void Quit();
   virtual void ScheduleWork();
   virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time);
 
  protected:
   // Returns the dispatcher for the current run state (|state_->dispatcher|).
-  Dispatcher* GetDispatcher();
+  MessagePumpDispatcher* GetDispatcher();
 
-  ObserverList<Observer>& observers() { return observers_; }
+  ObserverList<MessagePumpObserver>& observers() { return observers_; }
 
  private:
   // We may make recursive calls to Run, so we save state that needs to be
   // separate between them in this structure type.
   struct RunState;
 
-  // 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);
-
   RunState* state_;
 
   // This is a GLib structure that we can add event sources to.  We use the
   // default GLib context, which is the one to which all GTK events are
   // dispatched.
   GMainContext* context_;
 
   // This is the time when we need to do delayed work.
   TimeTicks delayed_work_time_;
 
   // The work source.  It is shared by all calls to Run and destroyed when
   // the message pump is destroyed.
   GSource* work_source_;
 
   // We use a wakeup pipe to make sure we'll get out of the glib polling phase
   // when another thread has scheduled us to do some work.  There is a glib
   // mechanism g_main_context_wakeup, but this won't guarantee that our event's
   // Dispatch() will be called.
   int wakeup_pipe_read_;
   int wakeup_pipe_write_;
   // Use a scoped_ptr to avoid needing the definition of GPollFD in the header.
   scoped_ptr<GPollFD> wakeup_gpollfd_;
 
   // List of observers.
-  ObserverList<Observer> observers_;
+  ObserverList<MessagePumpObserver> observers_;
 
-  DISALLOW_COPY_AND_ASSIGN(MessagePumpForUI);
+  DISALLOW_COPY_AND_ASSIGN(MessagePumpGlib);
 };
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_PUMP_GLIB_H_