Make --enable-benchmarking not affect metrics recording.

ios/chrome/browser/chrome_switches.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ios/chrome/browser/chrome_switches.h"
 
 namespace switches {
 
 // -----------------------------------------------------------------------------
 // When commenting your switch, please use the same voice as surrounding
@@ skipping 80 matching lines @@
 const char kEnableIOSPhysicalWeb[] = "enable-ios-physical-web";
 
 // Enables the Suggestions UI
 const char kEnableSuggestionsUI[] = "enable-suggestions-ui";
 
 // Forces additional Chrome Variation Ids that will be sent in X-Client-Data
 // header, specified as a 64-bit encoded list of numeric experiment ids. Ids
 // 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";
 
 // These mappings only apply to the host resolver.
 const char kIOSHostResolverRules[] = "host-resolver-rules";
 
 // Ignores certificate-related errors.
 const char kIOSIgnoreCertificateErrors[] = "ignore-certificate-errors";
 
 // Allows for forcing socket connections to http/https to use fixed ports.
 const char kIOSTestingFixedHttpPort[] = "testing-fixed-http-port";
 const char kIOSTestingFixedHttpsPort[] = "testing-fixed-https-port";
 
 }  // namespace switches