Merge subprocess metrics into global StatisticsRecorder.

components/metrics/metrics_provider.cc

Index: components/metrics/metrics_provider.cc
diff --git a/components/metrics/metrics_provider.cc b/components/metrics/metrics_provider.cc
index 2d6c191a491441beab00acda6f2cadbf35c22bc6..924cc6f318007b460cfd5eac148f92e3b4cda53d 100644
--- a/components/metrics/metrics_provider.cc
+++ b/components/metrics/metrics_provider.cc
@@ -47,6 +47,9 @@ void MetricsProvider::ProvideGeneralMetrics(
     ChromeUserMetricsExtension* uma_proto) {
 }
 
+void MetricsProvider::MergeHistogramDeltas() {
+}
+
 void MetricsProvider::RecordHistogramSnapshots(
     base::HistogramSnapshotManager* snapshot_manager) {
 }