Replace scoped_ptr with unique_ptr in webrtc/voice_engine/

Also introduce a pair of scoped_ptr <-> unique_ptr conversion
functions. By using them judiciously, we can keep these CL:s small and
avoid having to convert enormous amounts of code at once.

BUG=webrtc:5520

Review URL: https://codereview.webrtc.org/1702983002

Cr-Original-Commit-Position: refs/heads/master@{#11658}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: b7f89d6e668602e46a20e3a9927790ff34029b2a
diff --git a/voice_engine/channel_proxy.h b/voice_engine/channel_proxy.h
index 9d6839c..3461cf3 100644
--- a/voice_engine/channel_proxy.h
+++ b/voice_engine/channel_proxy.h
@@ -15,6 +15,7 @@
 #include "webrtc/voice_engine/channel_manager.h"
 #include "webrtc/voice_engine/include/voe_rtp_rtcp.h"
 
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -69,7 +70,7 @@
   virtual bool SetSendTelephoneEventPayloadType(int payload_type);
   virtual bool SendTelephoneEventOutband(uint8_t event, uint32_t duration_ms);
 
-  virtual void SetSink(rtc::scoped_ptr<AudioSinkInterface> sink);
+  virtual void SetSink(std::unique_ptr<AudioSinkInterface> sink);
 
  private:
   Channel* channel() const;