EDK: Sprinkle some more |final| secret sauce.

mojo/edk/util/mutex.h

 // Copyright 2015 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.
 
 // A mutex class, with support for thread annotations.
 //
 // TODO(vtl): Add support for non-exclusive (reader) locks.
 
 #ifndef MOJO_EDK_UTIL_MUTEX_H_
 #define MOJO_EDK_UTIL_MUTEX_H_
 
 #include <pthread.h>
 
 #include "mojo/edk/util/thread_annotations.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
 namespace util {
 
 // Mutex -----------------------------------------------------------------------
 
 class CondVar;
 
-class MOJO_LOCKABLE Mutex {
+class MOJO_LOCKABLE Mutex final {
  public:
 #if defined(NDEBUG) && !defined(DCHECK_ALWAYS_ON)
   Mutex() { pthread_mutex_init(&impl_, nullptr); }
   ~Mutex() { pthread_mutex_destroy(&impl_); }
 
   // Takes an exclusive lock.
   void Lock() MOJO_EXCLUSIVE_LOCK_FUNCTION() { pthread_mutex_lock(&impl_); }
 
   // Releases a lock.
   void Unlock() MOJO_UNLOCK_FUNCTION() { pthread_mutex_unlock(&impl_); }
@@ skipping 21 matching lines @@
  private:
   friend class CondVar;
 
   pthread_mutex_t impl_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(Mutex);
 };
 
 // MutexLocker -----------------------------------------------------------------
 
-class MOJO_SCOPED_LOCKABLE MutexLocker {
+class MOJO_SCOPED_LOCKABLE MutexLocker final {
  public:
   explicit MutexLocker(Mutex* mutex) MOJO_EXCLUSIVE_LOCK_FUNCTION(mutex)
       : mutex_(mutex) {
     this->mutex_->Lock();
   }
   ~MutexLocker() MOJO_UNLOCK_FUNCTION() { this->mutex_->Unlock(); }
 
  private:
   Mutex* const mutex_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MutexLocker);
 };
 
 }  // namespace util
 }  // namespace mojo
 
 #endif  // MOJO_EDK_UTIL_MUTEX_H_