base: Fix file_util_win.cc temp file random name generation.

Currently, the temporary directory name is generated by rand(), which was seeded with the number of seconds since Epoch. This was flaky when many directories were generated within a second, such as within a unit test.

This fix changes it to use base::rand_util.

BUG=NONE

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=206796

[tommycli, 2013-05-20 18:51:30]

brettw: Fixes temporary directory random name generation. Previously, random
name was seeded by seconds from epoch, which is problematic when many
directories are made within a second, such as in a unit test. Need review.

[tommycli, 2013-05-28 20:14:46]

brettw: ping for bugfix OWNER review.

[tommycli, 2013-06-11 15:22:58]

darin/brettw/willchan: Ping for OWNER review.

[tommycli, 2013-06-17 18:07:21]

mark: Also, need OWNER review on simple base/ bugfix.

[willchan no longer on Chromium, 2013-06-17 18:13:20]

LGTM

[commit-bot: I haz the power, 2013-06-17 18:25:48]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/tommycli@chromium.org/15479003/1

[commit-bot: I haz the power, 2013-06-17 18:25:49]

Failed to apply patch for base/file_util_win.cc:
While running patch -p1 --forward --force --no-backup-if-mismatch;
  patching file base/file_util_win.cc
  Hunk #1 FAILED at 18.
  1 out of 3 hunks FAILED -- saving rejects to file base/file_util_win.cc.rej

Patch:       base/file_util_win.cc
Index: base/file_util_win.cc
diff --git a/base/file_util_win.cc b/base/file_util_win.cc
index
47c59cf344f92f00bc39edbb15fbb308aa497c97..06c7d678ebee454b71deb631863a37d46c3f20cd
100644
--- a/base/file_util_win.cc
+++ b/base/file_util_win.cc
@@ -18,6 +18,7 @@
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/process_util.h"
+#include "base/rand_util.h"
 #include "base/string_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/threading/thread_restrictions.h"
@@ -371,7 +372,6 @@ bool CreateTemporaryDirInDir(const FilePath& base_dir,
   base::ThreadRestrictions::AssertIOAllowed();
 
   FilePath path_to_create;
-  srand(static_cast<uint32>(time(NULL)));
 
   for (int count = 0; count < 50; ++count) {
     // Try create a new temporary directory with random generated name. If
@@ -380,7 +380,7 @@ bool CreateTemporaryDirInDir(const FilePath& base_dir,
     new_dir_name.assign(prefix);
     new_dir_name.append(base::IntToString16(::base::GetCurrentProcId()));
     new_dir_name.push_back('_');
-    new_dir_name.append(base::IntToString16(rand() % kint16max));
+    new_dir_name.append(base::IntToString16(base::RandInt(0, kint16max)));
 
     path_to_create = base_dir.Append(new_dir_name);
     if (::CreateDirectory(path_to_create.value().c_str(), NULL)) {

[commit-bot: I haz the power, 2013-06-17 18:36:22]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/tommycli@chromium.org/15479003/9001

[commit-bot: I haz the power, 2013-06-17 21:06:41]

Change committed as 206796