Add monitoring for expired ignore rules.

golden/go/skiacorrectness/main.go

Index: golden/go/skiacorrectness/main.go
diff --git a/golden/go/skiacorrectness/main.go b/golden/go/skiacorrectness/main.go
index 86f06d3d59de5048f6f77d7ac985bdc3b530aae1..3272a65b3e1400dc8fb57251b32ac68873cda74a 100644
--- a/golden/go/skiacorrectness/main.go
+++ b/golden/go/skiacorrectness/main.go
@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/gorilla/mux"
+	"github.com/rcrowley/go-metrics"
 	"github.com/skia-dev/glog"
 	"go.skia.org/infra/go/auth"
 	"go.skia.org/infra/go/common"
@@ -369,6 +370,10 @@ func main() {
 		NCommits:          *nCommits,
 	}
 
+	if err := ignore.StartMonitoring(storages.IgnoreStore, metrics.DefaultRegistry); err != nil {

[stephana, 2015/04/13 13:56:57]

How about calling this Init and setting the DefaultRegistry in the Init function
? So it would be something like this:

if err := ignore.Init(storages)
... 


It think that pattern is desirable when we are never going to have more than one
instance of a type in an app. 

[jcgregorio, 2015/04/13 14:10:59]

Done.

+		glog.Fatalf("Failed to start monitoring for expired ignore rules: %s", err)
+	}
+
 	// Enable the experimental features.
 	if *startExperimental {
 		tallies, err = tally.New(storages)