Reduce header dependencies in base/

base/perftimer.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.
 
 #ifndef BASE_PERFTIMER_H_
 #define BASE_PERFTIMER_H_
 
 #include <string>
+
 #include "base/basictypes.h"
-#include "base/file_path.h"
 #include "base/time.h"
 
+class FilePath;
+
 // ----------------------------------------------------------------------
 // Initializes and finalizes the perf log. These functions should be
 // called at the beginning and end (respectively) of running all the
 // performance tests. The init function returns true on success.
 // ----------------------------------------------------------------------
 bool InitPerfLog(const FilePath& log_path);
 void FinalizePerfLog();
 
 // ----------------------------------------------------------------------
 // LogPerfResult
@@ skipping 49 matching lines @@
     logged_ = true;
   }
 
  private:
   bool logged_;
   std::string test_name_;
   PerfTimer timer_;
 };
 
 #endif  // BASE_PERFTIMER_H_