Fix more disabled MSVC warnings, base/ edition.

base/files/file_util.cc

 // Copyright (c) 2012 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.
 
 #include "base/files/file_util.h"
 
 #if defined(OS_WIN)
 #include <io.h>
 #endif
 #include <stdio.h>
@@ skipping 57 matching lines @@
     return false;
 
   const int BUFFER_SIZE = 2056;
   char buffer1[BUFFER_SIZE], buffer2[BUFFER_SIZE];
   do {
     file1.read(buffer1, BUFFER_SIZE);
     file2.read(buffer2, BUFFER_SIZE);
 
     if ((file1.eof() != file2.eof()) ||
         (file1.gcount() != file2.gcount()) ||
-        (memcmp(buffer1, buffer2, file1.gcount()))) {
+        (memcmp(buffer1, buffer2, static_cast<size_t>(file1.gcount())))) {
       file1.close();
       file2.close();
       return false;
     }
   } while (!file1.eof() || !file2.eof());
 
   file1.close();
   file2.close();
   return true;
 }
@@ skipping 162 matching lines @@
     if (!PathExists(new_path) &&
         (!have_suffix || !PathExists(FilePath(new_path.value() + suffix)))) {
       return count;
     }
   }
 
   return -1;
 }
 
 }  // namespace base