Cleanup usage of scoped_ptr<> in remoting for C++11

remoting/protocol/content_description.cc

Index: remoting/protocol/content_description.cc
diff --git a/remoting/protocol/content_description.cc b/remoting/protocol/content_description.cc
index 3c04c4a7a2d656e26b9dc0dbbf984e7d2acfb981..ef9dca14d66c623d112efb57b854452478b07d3e 100644
--- a/remoting/protocol/content_description.cc
+++ b/remoting/protocol/content_description.cc
@@ -214,7 +214,7 @@ scoped_ptr<ContentDescription> ContentDescription::ParseXml(
     const XmlElement* element) {
   if (element->Name() != QName(kChromotingXmlNamespace, kDescriptionTag)) {
     LOG(ERROR) << "Invalid description: " << element->Str();
-    return scoped_ptr<ContentDescription>();
+    return nullptr;
   }
   scoped_ptr<CandidateSessionConfig> config(
       CandidateSessionConfig::CreateEmpty());
@@ -226,7 +226,7 @@ scoped_ptr<ContentDescription> ContentDescription::ParseXml(
                            config->mutable_video_configs()) ||
       !ParseChannelConfigs(element, kAudioTag, true, true,
                            config->mutable_audio_configs())) {
-    return scoped_ptr<ContentDescription>();
+    return nullptr;
   }
 
   scoped_ptr<XmlElement> authenticator_message;