Convert most of base and net to use base::File

net/disk_cache/simple/simple_index_file.cc

Index: net/disk_cache/simple/simple_index_file.cc
diff --git a/net/disk_cache/simple/simple_index_file.cc b/net/disk_cache/simple/simple_index_file.cc
index 37ed234ab1635d367e95c188770e8892b6b74164..9e28a1229e45e2fea6b178f57c11820849502faa 100644
--- a/net/disk_cache/simple/simple_index_file.cc
+++ b/net/disk_cache/simple/simple_index_file.cc
@@ -195,7 +195,6 @@ void SimpleIndexFile::SyncWriteToDisk(net::CacheType cache_type,
   // part of a Create operation does not fit into the time budget for the index
   // flush delay. This simple approach will be reconsidered if it does not allow
   // for maintaining freshness.
-  base::PlatformFileInfo cache_dir_info;
   base::Time cache_dir_mtime;
   if (!simple_util::GetMTime(cache_directory, &cache_dir_mtime)) {
     LOG(ERROR) << "Could obtain information about cache age";