Show a warning message if the cache might not be cleared between runs.

webkit/tools/test_shell/test_shell.cc

 // Copyright (c) 2009 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.
 
 #undef LOG
 
 #include "webkit/tools/test_shell/test_shell.h"
 
 #include "base/base_paths.h"
 #include "base/command_line.h"
@@ skipping 791 matching lines @@
 }
 
 void ClearCache() {
   // Used in benchmarking,  Ignored for test_shell.
 }
 
 std::string GetProductVersion() {
   return std::string("Chrome/0.0.0.0");
 }
 
+bool IsSingleProcess() {
+  return true;
+}
+
 }  // namespace webkit_glue