PrependWrapper is platform-specific, so it should take a platform string.

chrome/browser/worker_host/worker_process_host.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.
 
 #include "chrome/browser/worker_host/worker_process_host.h"
 
 #include <set>
 #include <vector>
 
 #include "base/callback.h"
@@ skipping 125 matching lines @@
     }
   }
 
   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kDebugChildren)) {
     // Look to pass-on the kDebugOnStart flag.
     std::string value = CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
         switches::kDebugChildren);
     if (value.empty() || value == switches::kWorkerProcess) {
       // launches a new xterm, and runs the worker process in gdb, reading
       // optional commands from gdb_chrome file in the working directory.
-      cmd_line->PrependWrapper(L"xterm -e gdb -x gdb_chrome --args");
+      cmd_line->PrependWrapper("xterm -e gdb -x gdb_chrome --args");
     }
   }
 
   if (CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kRendererCmdPrefix)) {
-    const std::wstring prefix =
-        CommandLine::ForCurrentProcess()->GetSwitchValue(
-            switches::kRendererCmdPrefix);
-    cmd_line->PrependWrapper(prefix);
+    cmd_line->PrependWrapper(
+        CommandLine::ForCurrentProcess()->GetSwitchValueNative(
+            switches::kRendererCmdPrefix));
   }
 #endif
 
   Launch(
 #if defined(OS_WIN)
       FilePath(),
 #elif defined(OS_POSIX)
       false,
       base::environment_vector(),
 #endif
@@ skipping 432 matching lines @@
     }
   }
   return false;
 }
 
 WorkerProcessHost::WorkerInstance::SenderInfo
 WorkerProcessHost::WorkerInstance::GetSender() const {
   DCHECK(NumSenders() == 1);
   return *senders_.begin();
 }