Enabling 'gn check' on webrtc/sdk

webrtc/sdk/objc/Framework/Classes/RTCFieldTrials.mm

 /*
  *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #import "WebRTC/RTCFieldTrials.h"
 
 #include <memory>
 
 #import "WebRTC/RTCLogging.h"
 
-#include "webrtc/system_wrappers/include/field_trial_default.h"
+// Adding 'nogncheck' to disable the gn include headers check.
+// We don't want to depend on 'system_wrappers:field_trial_default' because
+// clients should be able to provide their own implementation.
+#include "webrtc/system_wrappers/include/field_trial_default.h"  // nogncheck
 
 NSString * const kRTCFieldTrialAudioSendSideBweKey = @"WebRTC-Audio-SendSideBwe";
 NSString * const kRTCFieldTrialSendSideBweWithOverheadKey = @"WebRTC-SendSideBwe-WithOverhead";
 NSString * const kRTCFieldTrialFlexFec03AdvertisedKey = @"WebRTC-FlexFEC-03-Advertised";
 NSString * const kRTCFieldTrialFlexFec03Key = @"WebRTC-FlexFEC-03";
 NSString * const kRTCFieldTrialImprovedBitrateEstimateKey = @"WebRTC-ImprovedBitrateEstimate";
 NSString * const kRTCFieldTrialMedianSlopeFilterKey = @"WebRTC-BweMedianSlopeFilter";
 NSString * const kRTCFieldTrialTrendlineFilterKey = @"WebRTC-BweTrendlineFilter";
 NSString * const kRTCFieldTrialH264HighProfileKey = @"WebRTC-H264HighProfile";
 NSString * const kRTCFieldTrialEnabledValue = @"Enabled";
@@ skipping 27 matching lines @@
   size_t len = fieldTrialInitString.length + 1;
   gFieldTrialInitString.reset(new char[len]);
   if (![fieldTrialInitString getCString:gFieldTrialInitString.get()
                               maxLength:len
                                encoding:NSUTF8StringEncoding]) {
     RTCLogError(@"Failed to convert field trial string.");
     return;
   }
   webrtc::field_trial::InitFieldTrialsFromString(gFieldTrialInitString.get());
 }