Add an unconditional version of DispatcherAddAwakable(): AddAwakableUnconditional().

mojo/edk/system/wait_set_dispatcher.h

 // Copyright 2016 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_EDK_SYSTEM_WAIT_SET_DISPATCHER_H_
 #define MOJO_EDK_SYSTEM_WAIT_SET_DISPATCHER_H_
 
 #include "mojo/edk/system/dispatcher.h"
 #include "mojo/public/cpp/system/macros.h"
 
@@ skipping 47 matching lines @@
       UserPointer<const MojoWaitSetAddOptions> options,
       Handle&& handle,
       MojoHandleSignals signals,
       uint64_t cookie) override;
   MojoResult WaitSetRemoveImplNoLock(uint64_t cookie) override;
   MojoResult WaitSetWaitImpl(MojoDeadline deadline,
                              UserPointer<uint32_t> num_results,
                              UserPointer<MojoWaitSetResult> results,
                              UserPointer<uint32_t> max_results) override;
 
- private:
   MOJO_DISALLOW_COPY_AND_ASSIGN(WaitSetDispatcher);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_WAIT_SET_DISPATCHER_H_