Use PlatformThreadId, not int when dealing with thread ids.

base/simple_thread.h

 // Copyright (c) 2006-2008 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.
 
 // WARNING: You should probably be using Thread (thread.h) instead.  Thread is
 //          Chrome's message-loop based Thread abstraction, and if you are a
 //          thread running in the browser, there will likely be assumptions
 //          that your thread will have an associated message loop.
 //
 // This is a simple thread interface that backs to a native operating system
@@ skipping 80 matching lines @@
   // Subclasses should override the Run method.
   virtual void Run() = 0;
 
   // Return the thread name prefix, or "unnamed" if none was supplied.
   std::string name_prefix() { return name_prefix_; }
 
   // Return the completed name including TID, only valid after Start().
   std::string name() { return name_; }
 
   // Return the thread id, only valid after Start().
-  int tid() { return tid_; }
+  PlatformThreadId tid() { return tid_; }
 
   // Return True if Start() has ever been called.
   bool HasBeenStarted() { return event_.IsSignaled(); }
 
   // Return True if Join() has evern been called.
   bool HasBeenJoined() { return joined_; }
 
  private:
   const std::string name_prefix_;
   std::string name_;
   const Options options_;
   PlatformThreadHandle thread_;  // PlatformThread handle, invalid after Join!
   WaitableEvent event_;          // Signaled if Start() was ever called.
-  int tid_;                      // The backing thread's id.
+  PlatformThreadId tid_;         // The backing thread's id.
   bool joined_;                  // True if Join has been called.
 };
 
 class DelegateSimpleThread : public SimpleThread {
  public:
   class Delegate {
    public:
     Delegate() { }
     virtual ~Delegate() { }
     virtual void Run() = 0;
@@ skipping 54 matching lines @@
   int num_threads_;
   std::vector<DelegateSimpleThread*> threads_;
   std::queue<Delegate*> delegates_;
   Lock lock_;            // Locks delegates_
   WaitableEvent dry_;    // Not signaled when there is no work to do.
 };
 
 }  // namespace base
 
 #endif  // BASE_SIMPLE_THREAD_H_