Remove OnRecordingDisabled() metrics client interface.

ios/chrome/browser/metrics/ios_chrome_metrics_service_client.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/metrics/ios_chrome_metrics_service_client.h"
 
 #include <stdint.h>
 
 #include <utility>
 #include <vector>
@@ skipping 84 matching lines @@
 
 metrics::MetricsService* IOSChromeMetricsServiceClient::GetMetricsService() {
   return metrics_service_.get();
 }
 
 void IOSChromeMetricsServiceClient::SetMetricsClientId(
     const std::string& client_id) {
   crash_keys::SetMetricsClientIdFromGUID(client_id);
 }
 
-void IOSChromeMetricsServiceClient::OnRecordingDisabled() {
-  crash_keys::ClearMetricsClientId();
-}
-
 bool IOSChromeMetricsServiceClient::IsOffTheRecordSessionActive() {
   return ::IsOffTheRecordSessionActive();
 }
 
 int32_t IOSChromeMetricsServiceClient::GetProduct() {
   return metrics::ChromeUserMetricsExtension::CHROME;
 }
 
 std::string IOSChromeMetricsServiceClient::GetApplicationLocale() {
   return GetApplicationContext()->GetApplicationLocale();
@@ skipping 196 matching lines @@
 
 void IOSChromeMetricsServiceClient::OnURLOpenedFromOmnibox(OmniboxLog* log) {
   metrics_service_->OnApplicationNotIdle();
 }
 
 metrics::EnableMetricsDefault
 IOSChromeMetricsServiceClient::GetMetricsReportingDefaultState() {
   return metrics::GetMetricsReportingDefaultState(
       GetApplicationContext()->GetLocalState());
 }