base: Do not allow MessagePumpObservers to consume events.

base/message_loop/message_pump_observer.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_OBSERVER_H
 #define BASE_MESSAGE_LOOP_MESSAGE_PUMP_OBSERVER_H
 
 #include "base/base_export.h"
 #include "base/event_types.h"
 
 namespace base {
 
-enum EventStatus {
-  EVENT_CONTINUE,    // The event should be dispatched as normal.
-#if defined(USE_X11)
-  EVENT_HANDLED      // The event should not be processed any farther.
-#endif
-};
-
 // A MessagePumpObserver is an object that receives global
 // notifications from the UI MessageLoop with MessagePumpWin or
 // MessagePumpX11.
 //
 // NOTE: An Observer implementation should be extremely fast!
 //
 // For use with MessagePumpX11, please see message_pump_glib.h for more
 // info about how this is invoked in this environment.
 class BASE_EXPORT MessagePumpObserver {
  public:
-  // This method is called before processing a NativeEvent. If the
-  // method returns EVENT_HANDLED, it indicates the event has already
-  // been handled, so the event is not processed any farther. If the
-  // method returns EVENT_CONTINUE, the event dispatching proceeds as
-  // normal.
-  virtual EventStatus WillProcessEvent(const NativeEvent& event) = 0;
+  // This method is called before processing a NativeEvent.
+  virtual void WillProcessEvent(const NativeEvent& event) = 0;
 
-  // This method is called after processing a message. This method
-  // will not be called if WillProcessEvent returns EVENT_HANDLED.
+  // This method is called after processing a message.
   virtual void DidProcessEvent(const NativeEvent& event) = 0;
 
  protected:
   virtual ~MessagePumpObserver() {}
 };
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_OBSERVER_H