Replace scoped_ptr with unique_ptr everywhere

But keep #including scoped_ptr.h in .h files, so as not to break
WebRTC users who expect those .h files to give them rtc::scoped_ptr.

BUG=webrtc:5520

Review-Url: https://codereview.webrtc.org/1937693002
Cr-Commit-Position: refs/heads/master@{#12581}
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCIceCandidate.mm b/webrtc/sdk/objc/Framework/Classes/RTCIceCandidate.mm
index 7b1e655..193403d 100644
--- a/webrtc/sdk/objc/Framework/Classes/RTCIceCandidate.mm
+++ b/webrtc/sdk/objc/Framework/Classes/RTCIceCandidate.mm
@@ -10,6 +10,8 @@
 
 #import "RTCIceCandidate+Private.h"
 
+#include <memory>
+
 #import "NSString+StdString.h"
 #import "WebRTC/RTCLogging.h"
 
@@ -51,7 +53,7 @@
                     sdpMid:[NSString stringForStdString:candidate->sdp_mid()]];
 }
 
-- (rtc::scoped_ptr<webrtc::IceCandidateInterface>)nativeCandidate {
+- (std::unique_ptr<webrtc::IceCandidateInterface>)nativeCandidate {
   webrtc::SdpParseError error;
 
   webrtc::IceCandidateInterface *candidate = webrtc::CreateIceCandidate(
@@ -63,7 +65,7 @@
            error.line.c_str());
   }
 
-  return rtc::scoped_ptr<webrtc::IceCandidateInterface>(candidate);
+  return std::unique_ptr<webrtc::IceCandidateInterface>(candidate);
 }
 
 @end