Convert SysInfo::AmountOfFreeDiskSpace from wstring to FilePath.

base/sys_info.h

 // Copyright (c) 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_SYS_INFO_H_
 #define BASE_SYS_INFO_H_
 
 #include "base/basictypes.h"
 
 #include <string>
 
+class FilePath;
+
 namespace base {
 
 class SysInfo {
  public:
   // Return the number of logical processors/cores on the current machine.
   static int NumberOfProcessors();
 
   // Return the number of bytes of physical memory on the current machine.
   static int64 AmountOfPhysicalMemory();
 
   // Return the number of megabytes of physical memory on the current machine.
   static int AmountOfPhysicalMemoryMB() {
     return static_cast<int>(AmountOfPhysicalMemory() / 1024 / 1024);
   }
 
   // Return the available disk space in bytes on the volume containing |path|,
   // or -1 on failure.
-  static int64 AmountOfFreeDiskSpace(const std::wstring& path);
+  static int64 AmountOfFreeDiskSpace(const FilePath& path);
 
   // Return true if the given environment variable is defined.
   // TODO: find a better place for HasEnvVar.
   static bool HasEnvVar(const wchar_t* var);
 
   // Return the value of the given environment variable
   // or an empty string if not defined.
   // TODO: find a better place for GetEnvVar.
   static std::wstring GetEnvVar(const wchar_t* var);
 
@@ skipping 40 matching lines @@
   static void ParseLsbRelease(const std::string& lsb_release,
                               int32 *major_version,
                               int32 *minor_version,
                               int32 *bugfix_version);
 #endif
 };
 
 }  // namespace base
 
 #endif  // BASE_SYS_INFO_H_