Consolidate win/x dispatchers

base/message_pump_dispatcher.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_PUMP_DISPATCHER_H
+#define BASE_MESSAGE_PUMP_DISPATCHER_H
+#pragma once
+
+#include "base/base_export.h"
+#include "base/event_types.h"
+
+namespace base {
+
+enum DispatchStatus {
+#if defined(USE_X11)
+  EVENT_IGNORED,    // The event was not processed. Used to handle gesture.
+                    // TODO(oshima|sadrul): Eliminate this enum and just use
+                    // bool once crbug.com/112329 is done.
+#endif
+  EVENT_PROCESSED,  // The event has been processed.
+  EVENT_QUIT        // The event was processed and the message-loop should
+                    // terminate.
+};
+
+// Dispatcher is used during a nested invocation of Run to dispatch
+// events when |MessageLoop::RunWithDispatcher| is invoked.  If
+// |MessageLoop::Run| is invoked, MessageLoop does not dispatch events
+// (or invoke TranslateMessage), rather every message 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 EVENT_QUIT
+// from Dispatch.
+class BASE_EXPORT MessagePumpDispatcher {
+ public:
+  virtual ~MessagePumpDispatcher() {}
+
+  // Dispatches the event. EVENT_IGNORED is returned if the event was
+  // ignored (i.e. not processed. X11 only). EVENT_PROCESSED is
+  // returned if the event was processed. The nested loop exits
+  // immediately if EVENT_QUIT is returned.
+  virtual DispatchStatus Dispatch(const NativeEvent& event) = 0;

[darin (slow to review), 2012/04/05 20:21:09]

it seems like there are really two flags here:

1-  was the event processed?
2-  should we keep going?

virtual void Dispatch(const NativeEvent& event,
                      bool* was_processed,
                      bool* should_quit) = 0;

+};
+
+}  // namespace base
+
+#endif  // BASE_MESSAGE_PUMP_DISPATCHER_H