Convert AutoComplete related code to StringRef.

Differential Revision: https://reviews.llvm.org/D26721

llvm-svn: 287188
diff --git a/lldb/source/Interpreter/OptionValueFileSpec.cpp b/lldb/source/Interpreter/OptionValueFileSpec.cpp
index f5c292d..a6eb537 100644
--- a/lldb/source/Interpreter/OptionValueFileSpec.cpp
+++ b/lldb/source/Interpreter/OptionValueFileSpec.cpp
@@ -101,11 +101,9 @@
   return OptionValueSP(new OptionValueFileSpec(*this));
 }
 
-size_t OptionValueFileSpec::AutoComplete(CommandInterpreter &interpreter,
-                                         const char *s, int match_start_point,
-                                         int max_return_elements,
-                                         bool &word_complete,
-                                         StringList &matches) {
+size_t OptionValueFileSpec::AutoComplete(
+    CommandInterpreter &interpreter, llvm::StringRef s, int match_start_point,
+    int max_return_elements, bool &word_complete, StringList &matches) {
   word_complete = false;
   matches.Clear();
   CommandCompletions::InvokeCommonCompletionCallbacks(