Replace the remaining scoped_ptr with unique_ptr in webrtc/modules/

BUG=webrtc:5520

Review URL: https://codereview.webrtc.org/1921233002

Cr-Commit-Position: refs/heads/master@{#12511}

webrtc/modules/rtp_rtcp/source/rtp_receiver_video.cc

@@ -13,6 +13,8 @@
 #include <assert.h>
 #include <string.h>
 
+#include <memory>
+
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/trace_event.h"
@@ -74,7 +76,7 @@ int32_t RTPReceiverVideo::ParseRtpPacket(WebRtcRTPHeader* rtp_header,
   }
 
   // We are not allowed to hold a critical section when calling below functions.
-  rtc::scoped_ptr<RtpDepacketizer> depacketizer(
+  std::unique_ptr<RtpDepacketizer> depacketizer(
       RtpDepacketizer::Create(rtp_header->type.Video.codec));
   if (depacketizer.get() == NULL) {
     LOG(LS_ERROR) << "Failed to create depacketizer.";