Remove duplicate implementations of string conversion methods.

webrtc/sdk/objc/Framework/Classes/helpers.h

 /*
  *  Copyright (c) 2015 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.
  */
 
 #ifndef WEBRTC_SDK_OBJC_FRAMEWORK_CLASSES_HELPERS_H_
 #define WEBRTC_SDK_OBJC_FRAMEWORK_CLASSES_HELPERS_H_
 
 #if defined(WEBRTC_IOS)
 
 #include <string>
 
 namespace webrtc {
 namespace ios {
 
 bool CheckAndLogError(BOOL success, NSError* error);
 
+NSString *NSStringFromStdString(const std::string& stdString);
 std::string StdStringFromNSString(NSString* nsString);
 
 // Return thread ID as a string.
 std::string GetThreadId();
 
 // Return thread ID as string suitable for debug logging.
 std::string GetThreadInfo();
 
 // Returns [NSThread currentThread] description as string.
 // Example: <NSThread: 0x170066d80>{number = 1, name = main}
@@ skipping 35 matching lines @@
 
 // Indicates whether Low Power Mode is enabled on the iOS device.
 bool GetLowPowerModeEnabled();
 
 }  // namespace ios
 }  // namespace webrtc
 
 #endif  // defined(WEBRTC_IOS)
 
 #endif  // WEBRTC_SDK_OBJC_FRAMEWORK_CLASSES_HELPERS_H_