base/files: Fixed two minor lint warnings.

Two changes identified by "git cl lint":

1. Removed unused <fstream>.
2. DCHECK -> DCHECK_EQ.

Review URL: https://codereview.chromium.org/707603003

Cr-Commit-Position: refs/heads/master@{#303723}


CrOS-Libchrome-Original-Commit: d3ca0b0220ec1b4756e640625e0332847a547591
diff --git a/base/files/file_util_posix.cc b/base/files/file_util_posix.cc
index b8c0eeb..0bf41a5 100644
--- a/base/files/file_util_posix.cc
+++ b/base/files/file_util_posix.cc
@@ -28,8 +28,6 @@
 #include <glib.h>  // for g_get_home_dir()
 #endif
 
-#include <fstream>
-
 #include "base/basictypes.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
@@ -428,7 +426,7 @@
 bool SetPosixFilePermissions(const FilePath& path,
                              int mode) {
   ThreadRestrictions::AssertIOAllowed();
-  DCHECK((mode & ~FILE_PERMISSION_MASK) == 0);
+  DCHECK_EQ(mode & ~FILE_PERMISSION_MASK, 0);
 
   // Calls stat() so that we can preserve the higher bits like S_ISGID.
   stat_wrapper_t stat_buf;