Make --enable-benchmarking not affect metrics recording.

ios/chrome/browser/chrome_switches.cc

Index: ios/chrome/browser/chrome_switches.cc
diff --git a/ios/chrome/browser/chrome_switches.cc b/ios/chrome/browser/chrome_switches.cc
index 624df12c3f86105b8d32082dbeb3a19b6b01e9a2..1c7fedebf61215e651801b77fba6e7e305366e69 100644
--- a/ios/chrome/browser/chrome_switches.cc
+++ b/ios/chrome/browser/chrome_switches.cc
@@ -98,13 +98,6 @@ const char kEnableSuggestionsUI[] = "enable-suggestions-ui";
 // prefixed with the character "t" will be treated as Trigger Variation Ids.
 const char kIOSForceVariationIds[] = "force-variation-ids";
 
-// 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 kIOSMetricsRecordingOnly[] = "metrics-recording-only";
-
 // A string used to override the default user agent with a custom one.
 const char kUserAgent[] = "user-agent";