[py3] Migrate ios/web_view PRESUBMIT

Bug: 1212043
Change-Id: Ibe095c197f4bdb01dfe4e7eedc3ab7d4da1bc00e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2957356
Commit-Queue: Mark Cogan <marq@chromium.org>
Auto-Submit: Josip Sokcevic <sokcevic@google.com>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#892007}
diff --git a/ios/web_view/PRESUBMIT.py b/ios/web_view/PRESUBMIT.py
index 14c85d8a..325e0587 100644
--- a/ios/web_view/PRESUBMIT.py
+++ b/ios/web_view/PRESUBMIT.py
@@ -10,6 +10,7 @@
 
 import os
 
+USE_PYTHON3 = True
 INCLUSION_PREFIXES = ('#import "', '#include "')