Milo: Add task expired as a failure status

common/proto/milo/annotations.proto

Index: common/proto/milo/annotations.proto
diff --git a/common/proto/milo/annotations.proto b/common/proto/milo/annotations.proto
index 76efd5460792b4316df8416fb6884d98bd85a5d8..418a2e40fc839446380c1bdbefbab47c9719cd8d 100644
--- a/common/proto/milo/annotations.proto
+++ b/common/proto/milo/annotations.proto
@@ -31,12 +31,15 @@ message FailureDetails {
     // The failure is related to a failed infrastructure component, not an error
     // with the Step itself.
     INFRA = 2;
+    // The failure was due to an resource exhausion. The step was scheduled
+    // but never ran, and never will run.
+    EXPIRED = 3;

[dnj, 2016/09/06 16:46:52]

NO, bad! This protobuf is already in play, and you cannot bump constant values.
Add this at the end after CANCELLED.

[hinoka, 2016/09/07 22:13:58]

Done.

     // The failure is due to a failed Dungeon Master dependency. This should be
     // used if a Step's external depdendency fails and the Step cannot recover
     // or proceed without it.
-    DM_DEPENDENCY_FAILED = 3;
+    DM_DEPENDENCY_FAILED = 4;
     // The step was cancelled.
-    CANCELLED = 4;
+    CANCELLED = 5;
   }
   Type type = 1;