Always use a /prefetch:# switch when launching a process on Windows.

chrome/app/chrome_exe_main_win.cc

 // Copyright (c) 2011 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 <windows.h>
 #include <malloc.h>
 #include <shellscalingapi.h>
 #include <stddef.h>
 #include <tchar.h>
 
@@ skipping 211 matching lines @@
   const std::string process_type =
       command_line->GetSwitchValueASCII(switches::kProcessType);
 
   startup_metric_utils::InitializePreReadOptions(
       BrowserDistribution::GetDistribution()->GetRegistryPath());
 
   // Confirm that an explicit prefetch profile is used for all process types
   // except for the browser process. Any new process type will have to assign
   // itself a prefetch id. See kPrefetchArgument* constants in
   // content_switches.cc for details.
-  DCHECK(!startup_metric_utils::GetPreReadOptions().use_prefetch_argument ||
-         process_type.empty() ||
+  DCHECK(process_type.empty() ||
          HasValidWindowsPrefetchArgument(*command_line));
 
   if (process_type == crash_reporter::switches::kCrashpadHandler) {
     return crash_reporter::RunAsCrashpadHandler(
         *base::CommandLine::ForCurrentProcess());
   }
 
   crash_reporter::SetCrashReporterClient(g_chrome_crash_client.Pointer());
   crash_reporter::InitializeCrashpadWithEmbeddedHandler(process_type.empty(),
                                                         process_type);
@@ skipping 14 matching lines @@
   RemoveAppCompatFlagsEntry();
 
   // Load and launch the chrome dll. *Everything* happens inside.
   VLOG(1) << "About to load main DLL.";
   MainDllLoader* loader = MakeMainDllLoader();
   int rc = loader->Launch(instance);
   loader->RelaunchChromeBrowserWithNewCommandLineIfNeeded();
   delete loader;
   return rc;
 }