Standardize usage of virtual/override/final in mojo/

mojo/edk/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_EDK_SYSTEM_SIMPLE_DISPATCHER_H_
 #define MOJO_EDK_SYSTEM_SIMPLE_DISPATCHER_H_
 
 #include <list>
 
 #include "base/macros.h"
 #include "mojo/edk/system/dispatcher.h"
 #include "mojo/edk/system/system_impl_export.h"
 #include "mojo/edk/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();
+  ~SimpleDispatcher() override;
 
   // To be called by subclasses when the state changes (so
   // |GetHandleSignalsStateImplNoLock()| should be checked again). Must be
   // called under lock.
   void HandleSignalsStateChangedNoLock();
 
   // |Dispatcher| protected methods:
-  virtual void CancelAllWaitersNoLock() override;
-  virtual MojoResult AddWaiterImplNoLock(
-      Waiter* waiter,
-      MojoHandleSignals signals,
-      uint32_t context,
-      HandleSignalsState* signals_state) override;
-  virtual void RemoveWaiterImplNoLock(
-      Waiter* waiter,
-      HandleSignalsState* signals_state) override;
+  void CancelAllWaitersNoLock() override;
+  MojoResult AddWaiterImplNoLock(Waiter* waiter,
+                                 MojoHandleSignals signals,
+                                 uint32_t context,
+                                 HandleSignalsState* signals_state) override;
+  void RemoveWaiterImplNoLock(Waiter* waiter,
+                              HandleSignalsState* signals_state) override;
 
  private:
   // Protected by |lock()|:
   WaiterList waiter_list_;
 
   DISALLOW_COPY_AND_ASSIGN(SimpleDispatcher);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_SIMPLE_DISPATCHER_H_