replace NULL->nullptr in src/remoting.

remoting/protocol/session_config.h

Index: remoting/protocol/session_config.h
diff --git a/remoting/protocol/session_config.h b/remoting/protocol/session_config.h
index 4246228a73996665b2a7f8b065636b32838c9917..c0313a04dda3dba942b99dbf2c1cdf11c2de59b9 100644
--- a/remoting/protocol/session_config.h
+++ b/remoting/protocol/session_config.h
@@ -138,7 +138,7 @@ class CandidateSessionConfig {
   }
 
   // Selects session configuration that is supported by both participants.
-  // NULL is returned if such configuration doesn't exist. When selecting
+  // nullptr is returned if such configuration doesn't exist. When selecting
   // channel configuration priority is given to the configs listed first
   // in |client_config|.
   bool Select(const CandidateSessionConfig* client_config,
@@ -150,7 +150,8 @@ class CandidateSessionConfig {
   // Extracts final protocol configuration. Must be used for the description
   // received in the session-accept stanza. If the selection is ambiguous
   // (e.g. there is more than one configuration for one of the channel)
-  // or undefined (e.g. no configurations for a channel) then NULL is returned.
+  // or undefined (e.g. no configurations for a channel) then nullptr is
+  // returned.
   bool GetFinalConfig(SessionConfig* result) const;
 
   scoped_ptr<CandidateSessionConfig> Clone() const;