Replace NULL with nullptr or null in webrtc/base/.

webrtc/base/scoped_autorelease_pool.h

Index: webrtc/base/scoped_autorelease_pool.h
diff --git a/webrtc/base/scoped_autorelease_pool.h b/webrtc/base/scoped_autorelease_pool.h
index 14a5c5f8d9a803594df22238130e7a75096a705b..2e0a2042dbf9f98f50d6d8dc92539c65eaf4b2c9 100644
--- a/webrtc/base/scoped_autorelease_pool.h
+++ b/webrtc/base/scoped_autorelease_pool.h
@@ -43,9 +43,9 @@ class ScopedAutoreleasePool {
   // as a stack object" discipline.
   //
   // Note: new is declared as "throw()" to get around a gcc warning about new
-  // returning NULL, but this method will never get called and therefore will
+  // returning null, but this method will never get called and therefore will
   // never actually throw any exception.
-  void* operator new(size_t size) throw() { return NULL; }
+  void* operator new(size_t size) throw() { return nullptr; }
   void operator delete (void* ptr) {}
 
   NSAutoreleasePool* pool_;