Convert SysInfo::AmountOfFreeDiskSpace from wstring to FilePath.

base/sys_info_win.cc

Index: base/sys_info_win.cc
diff --git a/base/sys_info_win.cc b/base/sys_info_win.cc
index 8e1a7bae5dd1dec8ec0e7e26f9ed0c64562509c7..ebb95c7bacdc38fb3faa1dd3b25d4ac0203a46d7 100644
--- a/base/sys_info_win.cc
+++ b/base/sys_info_win.cc
@@ -6,6 +6,7 @@
 
 #include <windows.h>
 
+#include "base/file_path.h"
 #include "base/logging.h"
 #include "base/scoped_ptr.h"
 #include "base/string_util.h"
@@ -35,9 +36,9 @@ int64 SysInfo::AmountOfPhysicalMemory() {
 }
 
 // static
-int64 SysInfo::AmountOfFreeDiskSpace(const std::wstring& path) {
+int64 SysInfo::AmountOfFreeDiskSpace(const FilePath& path) {
   ULARGE_INTEGER available, total, free;
-  if (!GetDiskFreeSpaceExW(path.c_str(), &available, &total, &free)) {
+  if (!GetDiskFreeSpaceExW(path.value().c_str(), &available, &total, &free)) {
     return -1;
   }
   int64 rv = static_cast<int64>(available.QuadPart);