Switching some interfaces to use std::unique_ptr<>.

webrtc/media/engine/webrtcvideocapturerfactory.cc

 /*
  *  Copyright (c) 2004 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.
  */
 
 #include <memory>
 
 #include "webrtc/media/engine/webrtcvideocapturer.h"
 #include "webrtc/media/engine/webrtcvideocapturerfactory.h"
 
 namespace cricket {
 
-VideoCapturer* WebRtcVideoDeviceCapturerFactory::Create(const Device& device) {
+std::unique_ptr<VideoCapturer> WebRtcVideoDeviceCapturerFactory::Create(
+    const Device& device) {
 #ifdef HAVE_WEBRTC_VIDEO
   std::unique_ptr<WebRtcVideoCapturer> capturer(
       new WebRtcVideoCapturer());
   if (!capturer->Init(device)) {
-    return nullptr;
+    return std::unique_ptr<VideoCapturer>();
   }
-  return capturer.release();
+  return std::move(capturer);
 #else
-  return nullptr;
+  return std::unique_ptr<VideoCapturer>();
 #endif
 }
 
 }  // namespace cricket