Remove implicit scoped_refptr operator T*

ppapi/thunk/ppb_file_chooser_thunk.cc

Index: ppapi/thunk/ppb_file_chooser_thunk.cc
diff --git a/ppapi/thunk/ppb_file_chooser_thunk.cc b/ppapi/thunk/ppb_file_chooser_thunk.cc
index c52125a42996325e31f636644e8d4b1e165c3b19..12dd62b515a89b8a9f748a1c0b5bc58327da8296 100644
--- a/ppapi/thunk/ppb_file_chooser_thunk.cc
+++ b/ppapi/thunk/ppb_file_chooser_thunk.cc
@@ -26,7 +26,7 @@ PP_Resource Create(PP_Instance instance,
     return 0;
   scoped_refptr<StringVar> string_var =
       StringVar::FromPPVar(accept_types);
-  std::string str = string_var ? string_var->value() : std::string();
+  std::string str = string_var.get() ? string_var->value() : std::string();
   return enter.functions()->CreateFileChooser(instance, mode, str.c_str());
 }