Don't call the other wait set impl dispatcher methods under mutex either.

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 36 matching lines @@
   bool SupportsEntrypointClass(EntrypointClass entrypoint_class) const override;
 
  private:
   WaitSetDispatcher();
   ~WaitSetDispatcher() override;
 
   // |Dispatcher| protected methods:
   util::RefPtr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock(
       MessagePipe* message_pipe,
       unsigned port) override;
-  MojoResult WaitSetAddImplNoLock(
-      UserPointer<const MojoWaitSetAddOptions> options,
-      Handle&& handle,
-      MojoHandleSignals signals,
-      uint64_t cookie) override;
-  MojoResult WaitSetRemoveImplNoLock(uint64_t cookie) override;
+  MojoResult WaitSetAddImpl(UserPointer<const MojoWaitSetAddOptions> options,
+                            Handle&& handle,
+                            MojoHandleSignals signals,
+                            uint64_t cookie) override;
+  MojoResult WaitSetRemoveImpl(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_