Remove base's implicit_cast.

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 c013084041f301cbd5ee378eb0642436d09ba910..11d37a95048b9093e57f3b4987dcd4c9a5d5e1e9 100644
--- a/net/disk_cache/simple/simple_index_file.cc
+++ b/net/disk_cache/simple/simple_index_file.cc
@@ -11,6 +11,7 @@
 #include "base/files/memory_mapped_file.h"
 #include "base/hash.h"
 #include "base/logging.h"
+#include "base/numerics/safe_conversions.h"
 #include "base/pickle.h"
 #include "base/single_thread_task_runner.h"
 #include "base/task_runner_util.h"
@@ -77,7 +78,7 @@ bool WritePickleFile(base::Pickle* pickle, const base::FilePath& file_name) {
 
   int bytes_written =
       file.Write(0, static_cast<const char*>(pickle->data()), pickle->size());
-  if (bytes_written != implicit_cast<int>(pickle->size())) {
+  if (bytes_written != base::checked_cast<int>(pickle->size())) {
     simple_util::SimpleCacheDeleteFile(file_name);
     return false;
   }