Mojo: Wrap the satisfied/unsatisfied wait flags state in a single object.

mojo/system/simple_dispatcher.h

 // Copyright 2013 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 MOJO_SYSTEM_SIMPLE_DISPATCHER_H_
 #define MOJO_SYSTEM_SIMPLE_DISPATCHER_H_
 
 #include <list>
 
 #include "base/basictypes.h"
 #include "mojo/system/dispatcher.h"
 #include "mojo/system/system_impl_export.h"
+#include "mojo/system/wait_flags_state.h"
 #include "mojo/system/waiter_list.h"
 
 namespace mojo {
 namespace system {
 
 // A base class for simple dispatchers. "Simple" means that there's a one-to-one
 // correspondence between handles and dispatchers (see the explanatory comment
 // in core.cc). This class implements the standard waiter-signalling mechanism
 // in that case.
 class MOJO_SYSTEM_IMPL_EXPORT SimpleDispatcher : public Dispatcher {
  protected:
   SimpleDispatcher();
   virtual ~SimpleDispatcher();
 
   // To be called by subclasses when the state changes (so
-  // |SatisfiedFlagsNoLock()| and |SatisfiableFlagsNoLock()| should be checked
-  // again). Must be called under lock.
-  void StateChangedNoLock();
+  // |GetWaitFlagsStateNoLock()| should be checked again). Must be called under
+  // lock.
+  void WaitFlagsStateChangedNoLock();
 
-  // These should return the wait flags that are satisfied by the object's
-  // current state and those that may eventually be satisfied by this object's
-  // state, respectively. They should be overridden by subclasses to reflect
-  // their notion of state. They are never called after the dispatcher has been
-  // closed. They are called under |lock_|.
-  virtual MojoWaitFlags SatisfiedFlagsNoLock() const = 0;
-  virtual MojoWaitFlags SatisfiableFlagsNoLock() const = 0;
+  // Never called after the dispatcher has been closed; called under |lock_|.
+  virtual WaitFlagsState GetWaitFlagsStateNoLock() const = 0;
 
   // |Dispatcher| protected methods:
   virtual void CancelAllWaitersNoLock() OVERRIDE;
   virtual MojoResult AddWaiterImplNoLock(Waiter* waiter,
                                          MojoWaitFlags flags,
                                          MojoResult wake_result) OVERRIDE;
   virtual void RemoveWaiterImplNoLock(Waiter* waiter) OVERRIDE;
 
  private:
   // Protected by |lock()|:
   WaiterList waiter_list_;
 
   DISALLOW_COPY_AND_ASSIGN(SimpleDispatcher);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_SIMPLE_DISPATCHER_H_