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

base/threading/thread_checker.h

 // 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.
 
-#ifndef BASE_THREAD_CHECKER_H_
-#define BASE_THREAD_CHECKER_H_
+#ifndef BASE_THREADING_THREAD_CHECKER_H_
+#define BASE_THREADING_THREAD_CHECKER_H_
 #pragma once
 
 #ifndef NDEBUG
 #include "base/lock.h"
-#include "base/platform_thread.h"
+#include "base/threading/platform_thread.h"
 #endif // NDEBUG
 
+namespace base {
+
 // Before using this class, please consider using NonThreadSafe as it
 // makes it much easier to determine the nature of your class.
 //
 // A helper class used to help verify that some methods of a class are
 // called from the same thread.  One can inherit from this class and use
 // CalledOnValidThread() to verify.
 //
 // Inheriting from class indicates that one must be careful when using the class
 // with multiple threads. However, it is up to the class document to indicate
 // how it can be used with threads.
@@ skipping 35 matching lines @@
 class ThreadChecker {
  public:
   bool CalledOnValidThread() const {
     return true;
   }
 
   void DetachFromThread() {}
 };
 #endif  // NDEBUG
 
-#endif  // BASE_THREAD_CHECKER_H_
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_CHECKER_H_