Clean up some nits in base::NativeLibrary.

base/native_library_ios.mm

 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/native_library.h"
 
 #include "base/logging.h"
 
 namespace base {
 
@@ skipping 11 matching lines @@
 }
 
 // static
 void UnloadNativeLibrary(NativeLibrary library) {
   NOTIMPLEMENTED();
   DCHECK(!library);
 }
 
 // static
 void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
-                                          const char* name) {
+                                          StringPiece name) {
   NOTIMPLEMENTED();
   return nullptr;
 }
 
 // static
-string16 GetNativeLibraryName(const string16& name) {
-  return name;
+string16 GetNativeLibraryName(StringPiece16 name) {
+  return name.as_string();
 }
 
 }  // namespace base