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

base/message_pump_gtk.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_GTK_H_
+#define BASE_MESSAGE_PUMP_GTK_H_
+#pragma once
+
+#include "base/message_pump_glib.h"
+
+typedef union _GdkEvent GdkEvent;
+
+namespace base {
+
+// The documentation for this class is in message_pump_glib.h
+class MessagePumpObserver {
+ 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() {}
+};
+
+// This class implements a message-pump for dispatching GTK events.
+class MessagePumpGtk : public MessagePumpGlib {

[Evan Martin, 2011/06/24 17:33:15]

Do these need BASE_API to not break the components build?

[sadrul, 2011/06/24 18:12:54]

It doesn't seem to be necessary at the moment, although it seems to be necessary
for message_pump_x. I am unsure if the difference makes sense.

+ public:
+  MessagePumpGtk();
+  virtual ~MessagePumpGtk();
+
+  // 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);

[Evan Martin, 2011/06/24 17:33:15]

Why virtual? Do we actually override this anywhere?

[sadrul, 2011/06/24 18:12:54]

Not at the moment. Removed 'virtual'.

+
+ private:
+  // Overridden from MessagePumpGlib
+  virtual bool RunOnce(GMainContext* context, bool block) OVERRIDE;
+
+  // 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);
+
+  DISALLOW_COPY_AND_ASSIGN(MessagePumpGtk);
+};
+
+typedef MessagePumpGtk MessagePumpForUI;
+
+}  // namespace base
+
+#endif  // BASE_MESSAGE_PUMP_GTK_H_