Add virtual and OVERRIDE to base/ implementation files

base/threading/worker_pool_posix.cc

 // Copyright (c) 2012 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.
 
 #include "base/threading/worker_pool_posix.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/debug/trace_event.h"
 #include "base/lazy_instance.h"
@@ skipping 44 matching lines @@
 base::LazyInstance<WorkerPoolImpl> g_lazy_worker_pool =
     LAZY_INSTANCE_INITIALIZER;
 
 class WorkerThread : public PlatformThread::Delegate {
  public:
   WorkerThread(const std::string& name_prefix,
                base::PosixDynamicThreadPool* pool)
       : name_prefix_(name_prefix),
         pool_(pool) {}
 
-  virtual void ThreadMain();
+  virtual void ThreadMain() OVERRIDE;
 
  private:
   const std::string name_prefix_;
   scoped_refptr<base::PosixDynamicThreadPool> pool_;
 
   DISALLOW_COPY_AND_ASSIGN(WorkerThread);
 };
 
 void WorkerThread::ThreadMain() {
   const std::string name = base::StringPrintf(
@@ skipping 103 matching lines @@
       return PendingTask(FROM_HERE, base::Closure());
     }
   }
 
   PendingTask pending_task = pending_tasks_.front();
   pending_tasks_.pop();
   return pending_task;
 }
 
 }  // namespace base