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 {
+
+// 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 whether or not to dispatch the event.
+//
+// The nested loop is exited by either posting a quit, or returning false
+// from Dispatch.
+class BASE_EXPORT MessagePumpDispatcher {
+ public:
+  virtual ~MessagePumpDispatcher() {}
+
+  // Dispatches the event. If true is returned processing continues as
+  // normal. If false is returned, the nested loop exits immediately.
+  virtual bool Dispatch(const NativeEvent& event) = 0;
+};
+
+}  // namespace base
+
+#endif  // BASE_MESSAGE_PUMP_DISPATCHER_H