Updates to base unittests so they run correctly in libchrome on Android

base/files/dir_reader_posix_unittest.cc

Index: base/files/dir_reader_posix_unittest.cc
diff --git a/base/files/dir_reader_posix_unittest.cc b/base/files/dir_reader_posix_unittest.cc
index 0685031a982c22772c8e187c5fc301578b9d0ea0..2e181b3d8517d9309f1e24e090fef2719901cf08 100644
--- a/base/files/dir_reader_posix_unittest.cc
+++ b/base/files/dir_reader_posix_unittest.cc
@@ -10,6 +10,7 @@
 #include <string.h>
 #include <unistd.h>
 
+#include "base/files/scoped_temp_dir.h"
 #include "base/logging.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -25,8 +26,9 @@ TEST(DirReaderPosixUnittest, Read) {
   if (DirReaderPosix::IsFallback())
     return;
 
-  char kDirTemplate[] = "/tmp/org.chromium.dir-reader-posix-XXXXXX";
-  const char* dir = mkdtemp(kDirTemplate);
+  base::ScopedTempDir temp_dir;
+  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  const char* dir = temp_dir.path().value().c_str();
   ASSERT_TRUE(dir);
 
   const int prev_wd = open(".", O_RDONLY | O_DIRECTORY);