Roll re2 193486d..db20d46.

https://chromium.googlesource.com/external/github.com/google/re2.git/+log/193486d..db20d46

BUG=694495

TBR=tfarina@chromium.org,thakis@chromium.org,ochang@chromium.org,

Review-Url: https://codereview.chromium.org/2705113006
Cr-Commit-Position: refs/heads/master@{#452463}
NOKEYCHECK=True
GitOrigin-RevId: ce2ff44b62a49ace0153ad19023fcd95e8be4312
diff --git a/README.chromium b/README.chromium
index a941175..730859a 100644
--- a/README.chromium
+++ b/README.chromium
@@ -1,8 +1,8 @@
 Name: re2 - an efficient, principled regular expression library
 Short Name: re2
 URL: https://github.com/google/re2
-Version: 193486d7164a40ce28d8ec64552df129c0558bad
-Date: 2017-02-17
+Version: db20d46c05900a12539225fe800dd860b14e0061
+Date: 2017-02-22
 License: BSD 3-Clause
 License File: LICENSE
 Security Critical: yes