validation_pool.py: shorten the timeout on submitting a patch

Given that we treat a timed out SUBMIT as thought the patch was
submitted, and are hitting this timeout quite often, there doesn't seem
to be much point in waiting so long. See for instance
http://goo.gl/1Taz3k

BUG=None
TEST=None

Change-Id: Iaaede53c62abd0962de4e85fafcfa6dad60b7da1
Reviewed-on: https://chromium-review.googlesource.com/191109
Tested-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Yu-Ju Hong <yjhong@chromium.org>
Commit-Queue: Aviv Keshet <akeshet@chromium.org>
diff --git a/buildbot/validation_pool.py b/buildbot/validation_pool.py
index 60d06d1..cd84df5 100644
--- a/buildbot/validation_pool.py
+++ b/buildbot/validation_pool.py
@@ -50,8 +50,8 @@
 CQ = 'cq'
 
 # The gerrit-on-borg team tells us that delays up to 2 minutes can be
-# normal.  Setting timeout to 8 minutes to be safe-ish.
-SUBMITTED_WAIT_TIMEOUT = 8 * 60 # Time in seconds.
+# normal.  Setting timeout to 3 minutes to be safe-ish.
+SUBMITTED_WAIT_TIMEOUT = 3 * 60 # Time in seconds.
 
 class TreeIsClosedException(Exception):
   """Raised when the tree is closed and we wanted to submit changes."""