Make --enable-benchmarking not affect metrics recording.

components/metrics/metrics_switches.cc

Index: components/metrics/metrics_switches.cc
diff --git a/components/metrics/metrics_switches.cc b/components/metrics/metrics_switches.cc
index 1aef619d6a4a9a56e03cca597d058536f8289dd1..f380ff8e7ce33f317595ea414c9dea4c5f0e45b9 100644
--- a/components/metrics/metrics_switches.cc
+++ b/components/metrics/metrics_switches.cc
@@ -7,6 +7,13 @@
 namespace metrics {
 namespace switches {
 
+// Enables the recording of metrics reports but disables reporting. In contrast
+// to kDisableMetrics, this executes all the code that a normal client would
+// use for reporting, except the report is dropped rather than sent to the
+// server. This is useful for finding issues in the metrics code during UI and
+// performance tests.
+const char kMetricsRecordingOnly[] = "metrics-recording-only";
+
 // Forces a reset of the one-time-randomized FieldTrials on this client, also
 // known as the Chrome Variations state.
 const char kResetVariationState[] = "reset-variation-state";