Move platform_thread to base/threading and put in the base namespace. I left ...

base/lock_unittest.cc

 // Copyright (c) 2010 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/lock.h"
 
 #include <stdlib.h>
 
-#include "base/platform_thread.h"
+#include "base/threading/platform_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+using base::kNullThreadHandle;
+using base::PlatformThread;
+using base::PlatformThreadHandle;
+
 typedef testing::Test LockTest;
 
 // Basic test to make sure that Acquire()/Release()/Try() don't crash ----------
 
 class BasicLockTestThread : public PlatformThread::Delegate {
  public:
   BasicLockTestThread(Lock* lock) : lock_(lock), acquired_(0) {}
 
   virtual void ThreadMain() {
     for (int i = 0; i < 10; i++) {
@@ skipping 182 matching lines @@
   ASSERT_TRUE(PlatformThread::Create(0, &thread3, &handle3));
 
   MutexLockTestThread::DoStuff(&lock, &value);
 
   PlatformThread::Join(handle1);
   PlatformThread::Join(handle2);
   PlatformThread::Join(handle3);
 
   EXPECT_EQ(4 * 40, value);
 }