DRT should handle relative path arguments.

webkit/support/webkit_support.cc

 // 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.
 
 #include "webkit/support/webkit_support.h"
 
 #include "base/at_exit.h"
 #include "base/base64.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 618 matching lines @@
 WebURL CreateURLForPathOrURL(const std::string& path_or_url_in_nativemb) {
   // NativeMB to UTF-8
   std::wstring wide_path_or_url
       = base::SysNativeMBToWide(path_or_url_in_nativemb);
   std::string path_or_url_in_utf8 = WideToUTF8(wide_path_or_url);
 
   GURL url(path_or_url_in_utf8);
   if (url.is_valid() && url.has_scheme())
     return WebURL(url);
 #if defined(OS_WIN)
-  return net::FilePathToFileURL(FilePath(wide_path_or_url));
+  FilePath path(wide_path_or_url);
 #else
-  return net::FilePathToFileURL(FilePath(path_or_url_in_nativemb));
+  FilePath path(path_or_url_in_nativemb);
 #endif
+  file_util::AbsolutePath(&path);
+  return net::FilePathToFileURL(path);
 }
 
 WebURL RewriteLayoutTestsURL(const std::string& utf8_url) {
   const char kPrefix[] = "file:///tmp/LayoutTests/";
   const int kPrefixLen = arraysize(kPrefix) - 1;
 
   if (utf8_url.compare(0, kPrefixLen, kPrefix, kPrefixLen))
     return WebURL(GURL(utf8_url));
 
   FilePath replacePath =
@@ skipping 213 matching lines @@
 // Logging
 void EnableWebCoreLogChannels(const std::string& channels) {
   webkit_glue::EnableWebCoreLogChannels(channels);
 }
 
 void SetGamepadData(const WebKit::WebGamepads& pads) {
   test_environment->webkit_platform_support()->setGamepadData(pads);
 }
 
 }  // namespace webkit_support