Use ASCII strings for switch names.

tools/imagediff/image_diff.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.
 
 // This file input format is based loosely on
 // WebKitTools/DumpRenderTree/ImageDiff.m
 
 // The exact format of this tool's output to stdout is important, to match
 // what the run-webkit-tests script expects.
 
@@ skipping 10 matching lines @@
 #include "base/process_util.h"
 #include "base/scoped_ptr.h"
 #include "base/string_util.h"
 
 #if defined(OS_WIN)
 #include "windows.h"
 #endif
 
 // Causes the app to remain open, waiting for pairs of filenames on stdin.
 // The caller is then responsible for terminating this app.
-static const wchar_t kOptionPollStdin[] = L"use-stdin";
-static const wchar_t kOptionGenerateDiff[] = L"diff";
+static const char kOptionPollStdin[] = "use-stdin";
+static const char kOptionGenerateDiff[] = "diff";
 
 // Return codes used by this utility.
 static const int kStatusSame = 0;
 static const int kStatusDifferent = 1;
 static const int kStatusError = 2;
 
 // Color codes.
 static const uint32 RGBA_RED = 0x000000ff;
 static const uint32 RGBA_ALPHA = 0xff000000;
 
@@ skipping 312 matching lines @@
                         WideToUTF8(values[1]).c_str(),
                         WideToUTF8(values[2]).c_str());
     }
   } else if (values.size() == 2) {
     return CompareImages(argv[1], argv[2]);
   }
 
   PrintHelp();
   return kStatusError;
 }