Add metrics to expconfigfetcher call

Tracks the time to call the expconfigfetcher and whether it updated the
config file or not.

Test:
Ran a build with a "regular" user and verified the metrics indicated
NO_CONFIG and no config file was created.
Ran a build with an "experiment" user and verified the metrics indicated
CONFIG and a googler.json config file was created.

Bug: http://b/227186589
Change-Id: I030e9497c369459ae98c0c4f7765aef6de4c601f
diff --git a/ui/metrics/metrics.go b/ui/metrics/metrics.go
index 6f1ed60..0c62865 100644
--- a/ui/metrics/metrics.go
+++ b/ui/metrics/metrics.go
@@ -38,6 +38,7 @@
 	"time"
 
 	"android/soong/shared"
+
 	"google.golang.org/protobuf/proto"
 
 	soong_metrics_proto "android/soong/ui/metrics/metrics_proto"
@@ -135,6 +136,11 @@
 	m.metrics.SystemResourceInfo = b
 }
 
+// ExpConfigFetcher stores information about the expconfigfetcher.
+func (m *Metrics) ExpConfigFetcher(b *soong_metrics_proto.ExpConfigFetcher) {
+	m.metrics.ExpConfigFetcher = b
+}
+
 // SetMetadataMetrics sets information about the build such as the target
 // product, host architecture and out directory.
 func (m *Metrics) SetMetadataMetrics(metadata map[string]string) {