relevant_changes: rename a constant

We refer to this feature all over the place as "history aware submit",
but the most important constant about it doesn't include the word
"history", making it hard to find.

BUG=None
TEST=grep for old name, no results

Change-Id: I4dd995b1c6800f3485a71cbe61edb66d05483306
Reviewed-on: https://chromium-review.googlesource.com/726306
Commit-Ready: Aviv Keshet <akeshet@chromium.org>
Tested-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Ningning Xia <nxia@chromium.org>
diff --git a/cbuildbot/relevant_changes.py b/cbuildbot/relevant_changes.py
index ecf3b17..bf39c1c 100644
--- a/cbuildbot/relevant_changes.py
+++ b/cbuildbot/relevant_changes.py
@@ -22,7 +22,7 @@
 
 # Limit (hours) for looking back cl actions in the history for history-aware
 # submission.
-CLACTION_LOOKBACK_LIMIT_HOUR = 48
+CQ_HISTORY_LOOKBACK_LIMIT_HOUR = 48
 
 
 site_config = config_lib.GetConfig()
@@ -149,7 +149,7 @@
   @classmethod
   def GetPreviouslyPassedSlavesForChanges(
       cls, master_build_id, db, changes, change_relevant_slaves_dict,
-      history_lookback_limit=CLACTION_LOOKBACK_LIMIT_HOUR):
+      history_lookback_limit=CQ_HISTORY_LOOKBACK_LIMIT_HOUR):
     """Get slaves passed in history (not from current run) for changes.
 
     If a previous slave build:
@@ -166,7 +166,7 @@
         slaves in current run.
       history_lookback_limit: Limit (hours) for looking back cl actions in the
         histor. If it's None, do not force the limit.
-        Default to CLACTION_LOOKBACK_LIMIT_HOUR.
+        Default to CQ_HISTORY_LOOKBACK_LIMIT_HOUR.
 
     Returns:
       A dict mapping changes (cros_patch.GerritPatch instances) to sets of