Reduce header dependencies in base/

base/field_trial.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.
 
 // FieldTrial is a class for handling details of statistical experiments
 // performed by actual users in the field (i.e., in a shipped or beta product).
 // All code is called exclusively on the UI thread currently.
 //
 // The simplest example is an experiment to see whether one of two options
 // produces "better" results across our user population.  In that scenario, UMA
@@ skipping 48 matching lines @@
 
 //------------------------------------------------------------------------------
 
 #ifndef BASE_FIELD_TRIAL_H_
 #define BASE_FIELD_TRIAL_H_
 
 #include <map>
 #include <string>
 
 #include "base/lock.h"
-#include "base/non_thread_safe.h"
 #include "base/ref_counted.h"
 #include "base/time.h"
 
 
 class FieldTrial : public base::RefCounted<FieldTrial> {
  public:
   static const int kNotParticipating;
 
   // Define a separator charactor to use when creating a persistent form of an
   // instance.  This is intended for use as a command line argument, passed to a
@@ skipping 120 matching lines @@
   base::Time application_start_time_;
 
   // Lock for access to registered_.
   Lock lock_;
   RegistrationList registered_;
 
   DISALLOW_COPY_AND_ASSIGN(FieldTrialList);
 };
 
 #endif  // BASE_FIELD_TRIAL_H_