rename metrics.go to metrics_proto.go. (#107)

diff --git a/metrics.go b/metrics_proto.go
similarity index 98%
rename from metrics.go
rename to metrics_proto.go
index c37cbad..e897f70 100644
--- a/metrics.go
+++ b/metrics_proto.go
@@ -43,7 +43,7 @@
 
 var errNilMetric = errors.New("expecting a non-nil metric")
 
-type metricPayload struct {
+type metricProtoPayload struct {
 	node     *commonpb.Node
 	resource *resourcepb.Resource
 	metric   *metricspb.Metric
@@ -56,7 +56,7 @@
 	}
 
 	for _, metric := range metrics {
-		payload := &metricPayload{
+		payload := &metricProtoPayload{
 			metric:   metric,
 			resource: rsc,
 			node:     node,
@@ -67,7 +67,7 @@
 	return nil
 }
 
-func (se *statsExporter) handleMetricsUpload(payloads []*metricPayload) error {
+func (se *statsExporter) handleMetricsProtoUpload(payloads []*metricProtoPayload) error {
 	ctx, cancel := se.o.newContextWithTimeout()
 	defer cancel()
 
diff --git a/metrics_test.go b/metrics_proto_test.go
similarity index 100%
rename from metrics_test.go
rename to metrics_proto_test.go
diff --git a/stats.go b/stats.go
index 9a404b8..c0f543e 100644
--- a/stats.go
+++ b/stats.go
@@ -108,9 +108,9 @@
 		vds := bundle.([]*view.Data)
 		e.handleUpload(vds...)
 	})
-	e.protoMetricsBundler = bundler.NewBundler((*metricPayload)(nil), func(bundle interface{}) {
-		payloads := bundle.([]*metricPayload)
-		e.handleMetricsUpload(payloads)
+	e.protoMetricsBundler = bundler.NewBundler((*metricProtoPayload)(nil), func(bundle interface{}) {
+		payloads := bundle.([]*metricProtoPayload)
+		e.handleMetricsProtoUpload(payloads)
 	})
 	if delayThreshold := e.o.BundleDelayThreshold; delayThreshold > 0 {
 		e.viewDataBundler.DelayThreshold = delayThreshold