Clang style plugin: remove 'warn-only' option

tools/clang/plugins/ChromeClassTester.cpp

 // Copyright (c) 2012 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.
 
 // A general interface for filtering and only acting on classes in Chromium C++
 // code.
 
 #include "ChromeClassTester.h"
 
 #include <algorithm>
@@ skipping 301 matching lines @@
     // If we're in an invalid location, we're looking at things that aren't
     // actually stated in the source.
     return false;
   }
 
   *filename = ploc.getFilename();
   return true;
 }
 
 DiagnosticsEngine::Level ChromeClassTester::getErrorLevel() {
-  if (options_.warn_only)
-    return DiagnosticsEngine::Warning;
-
   return diagnostic().getWarningsAsErrors() ? DiagnosticsEngine::Error
                                             : DiagnosticsEngine::Warning;
 }