Add missing import statement.

BUG=None
TEST=Testing by hand in role account.

Change-Id: If7657ae15bea5faee891e5ae9959082196d77e32
Reviewed-on: https://chrome-internal-review.googlesource.com/217513
Reviewed-by: Luis Lozano <llozano@chromium.org>
Commit-Queue: Caroline Tice <cmtice@google.com>
Tested-by: Caroline Tice <cmtice@google.com>
diff --git a/test_toolchains.py b/test_toolchains.py
index 2bcb617..4351340 100755
--- a/test_toolchains.py
+++ b/test_toolchains.py
@@ -1,6 +1,7 @@
 #!/usr/bin/python
 
 # Script to test different toolchains against ChromeOS benchmarks.
+import datetime
 import optparse
 import os
 import sys